Lucene Change Log

For more information on past and future Lucene versions, please see: http://s.apache.org/luceneversions

For "contrib" changes prior to 4.0, please see: http://svn.apache.org/repos/asf/lucene/dev/tags/lucene_solr_3_6_0/lucene/contrib/CHANGES.txt

Release 4.0.0

Changes in backwards compatibility policy (2)
1. LUCENE-4392: Class org.apache.lucene.util.SortedVIntList has been removed.
  (Adrien Grand)
2. LUCENE-4393: RollingCharBuffer has been moved to the o.a.l.analysis.util package of lucene-analysis-common.
  (Adrien Grand)
New Features (5)
1. LUCENE-1888: Added the option to store payloads in the term vectors (IndexableFieldType.storeTermVectorPayloads()). Note that you must store term vector positions to store payloads.
  (Robert Muir)
2. LUCENE-3892: Add a new BlockPostingsFormat that bulk-encodes docs, freqs and positions in large (size 128) packed-int blocks for faster search performance. This was from Han Jiang's 2012 Google Summer of Code project
  (Han Jiang, Adrien Grand, Robert Muir, Mike McCandless)
3. LUCENE-4323: Added support for an absolute maximum CFS segment size (in MiB) to LogMergePolicy and TieredMergePolicy.
  (Alexey Lef via Uwe Schindler)
4. LUCENE-4339: Allow deletes against 3.x segments for easier upgrading. Lucene3x Codec is still otherwise read-only, you should not set it as the default Codec on IndexWriter, because it cannot write new segments.
  (Mike McCandless, Robert Muir)
5. SOLR-3441: ElisionFilterFactory is now MultiTermAware
  (Jack Krupansky via hossman)
API Changes (15)
1. LUCENE-4391, LUCENE-4440: All methods of Lucene40Codec but getPostingsFormatForField are now final. To reuse functionality of Lucene40, you should extend FilterCodec and delegate to Lucene40 instead of extending Lucene40Codec.
  (Adrien Grand, Shai Erea, Robert Muir, Uwe Schindler)
2. LUCENE-4299: Added Terms.hasPositions() and Terms.hasOffsets(). Previously you had no real way to know that a term vector field had positions or offsets, since this can be configured on a per-field-per-document basis.
  (Robert Muir)
3. Removed DocsAndPositionsEnum.hasPayload() and simplified the contract of getPayload(). It returns null if there is no payload, otherwise returns the current payload. You can now call it multiple times per position if you want.
  (Robert Muir)
4. Removed FieldsEnum. Fields API instead implements Iterable<String> and exposes Iterator, so you can iterate over field names with for (String field : fields) instead.
  (Robert Muir)
5. LUCENE-4152: added IndexReader.leaves(), which lets you enumerate the leaf atomic reader contexts for all readers in the tree.
  (Uwe Schindler, Robert Muir)
6. LUCENE-4304: removed PayloadProcessorProvider. If you want to change payloads (or other things) when merging indexes, its recommended to just use a FilterAtomicReader + IndexWriter.addIndexes. See the OrdinalMappingAtomicReader and TaxonomyMergeUtils in the facets module if you want an example of this.
  (Mike McCandless, Uwe Schindler, Shai Erera, Robert Muir)
7. LUCENE-4304: Make CompositeReader.getSequentialSubReaders() protected. To get atomic leaves of any IndexReader use the new method leaves() (LUCENE-4152), which lists AtomicReaderContexts including the doc base of each leaf.
  (Uwe Schindler, Robert Muir)
8. LUCENE-4307: Renamed IndexReader.getTopReaderContext to IndexReader.getContext.
  (Robert Muir)
9. LUCENE-4316: Deprecate Fields.getUniqueTermCount and remove it from AtomicReader. If you really want the unique term count across all fields, just sum up Terms.size() across those fields. This method only exists so that this statistic can be accessed for Lucene 3.x segments, which don't support Terms.size().
  (Uwe Schindler, Robert Muir)
10. LUCENE-4321: Change CharFilter to extend Reader directly, as FilterReader overdelegates (read(), read(char[], int, int), skip, etc). This made it hard to implement CharFilters that were correct. Instead only close() is delegated by default: read(char[], int, int) and correct(int) are abstract so that its obvious which methods you should implement. The protected inner Reader is 'input' like CharFilter in the 3.x series, instead of 'in'.
  (Dawid Weiss, Uwe Schindler, Robert Muir)
11. LUCENE-3309: The expert FieldSelector API, used to load only certain fields in a stored document, has been replaced with the simpler StoredFieldVisitor API.
  (Mike McCandless)
12. LUCENE-4343: Made Tokenizer.setReader final. This is a setter that should not be overriden by subclasses: per-stream initialization should happen in reset().
  (Robert Muir)
13. LUCENE-4377: Remove IndexInput.copyBytes(IndexOutput, long). Use DataOutput.copyBytes(DataInput, long) instead.
  (Mike McCandless, Robert Muir)
14. LUCENE-4355: Simplify AtomicReader's sugar methods such as termDocsEnum, termPositionsEnum, docFreq, and totalTermFreq to only take Term as a parameter. If you want to do expert things such as pass a different Bits as liveDocs, then use the flex apis (fields(), terms(), etc) directly.
  (Mike McCandless, Robert Muir)
15. LUCENE-4425: clarify documentation of StoredFieldVisitor.binaryValue and simplify the api to binaryField(FieldInfo, byte[]).
  (Adrien Grand, Robert Muir)
Bug Fixes (17)
1. LUCENE-4423: DocumentStoredFieldVisitor.binaryField ignored offset and length.
  (Adrien Grand)
2. LUCENE-4297: BooleanScorer2 would multiply the coord() factor twice for conjunctions: for most users this is no problem, but if you had a customized Similarity that returned something other than 1 when overlap == maxOverlap (always the case for conjunctions), then the score would be incorrect.
  (Pascal Chollet, Robert Muir)
3. LUCENE-4298: MultiFields.getTermDocsEnum(IndexReader, Bits, String, BytesRef) did not work at all, it would infinitely recurse.
  (Alberto Paro via Robert Muir)
4. LUCENE-4300: BooleanQuery's rewrite was not always safe: if you had a custom Similarity where coord(1,1) != 1F, then the rewritten query would be scored differently.
  (Robert Muir)
5. Don't allow negatives in the positions file. If you have an index from 2.4.0 or earlier with such negative positions, and you already upgraded to 3.x, then to Lucene 4.0-ALPHA or -BETA, you should run CheckIndex. If it fails, then you need to upgrade again to 4.0
  (Robert Muir)
6. LUCENE-4303: PhoneticFilterFactory and SnowballPorterFilterFactory load their encoders / stemmers via the ResourceLoader now instead of Class.forName(). Solr users should now no longer have to embed these in its war.
  (David Smiley)
7. SOLR-3737: StempelPolishStemFilterFactory loaded its stemmer table incorrectly. Also, ensure immutability and use only one instance of this table in RAM (lazy loaded) since its quite large.
  (sausarkar, Steven Rowe, Robert Muir)
8. LUCENE-4310: MappingCharFilter was failing to match input strings containing non-BMP Unicode characters.
  (Dawid Weiss, Robert Muir, Mike McCandless)
9. LUCENE-4224: Add in-order scorer to query time joining and the out-of-order scorer throws an UOE.
  (Martijn van Groningen, Robert Muir)
10. LUCENE-4333: Fixed NPE in TermGroupFacetCollector when faceting on mv fields.
  (Jesse MacVicar, Martijn van Groningen)
11. LUCENE-4218: Document.get(String) and Field.stringValue() again return values for numeric fields, like Lucene 3.x and consistent with the documentation.
  (Jamie, Uwe Schindler, Robert Muir)
12. NRTCachingDirectory was always caching a newly flushed segment in RAM, instead of checking the estimated size of the segment to decide whether to cache it.
  (Mike McCandless)
13. LUCENE-3720: fix memory-consumption issues with BeiderMorseFilter.
  (Thomas Neidhart via Robert Muir)
14. LUCENE-4401: Fix bug where DisjunctionSumScorer would sometimes call score() on a subscorer that had already returned NO_MORE_DOCS.
  (Liu Chao, Robert Muir)
15. LUCENE-4411: when sampling is enabled for a FacetRequest, its depth parameter is reset to the default (1), even if set otherwise.
  (Gilad Barkai via Shai Erera)
16. LUCENE-4455: Fix bug in SegmentInfoPerCommit.sizeInBytes() that was returning 2X the true size, inefficiently. Also fixed bug in CheckIndex that would report no deletions when a segment has deletions, and vice/versa.
  (Uwe Schindler, Robert Muir, Mike McCandless)
17. LUCENE-4456: Fixed double-counting sizeInBytes for a segment (affects how merge policies pick merges); fixed CheckIndex's incorrect reporting of whether a segment has deletions; fixed case where on abort Lucene could remove files it didn't create; fixed many cases where IndexWriter could leave leftover files (on exception in various places, on reuse of a segment name after crash and recovery.
  (Uwe Schindler, Robert Muir, Mike McCandless)
Optimizations (4)
1. LUCENE-4322: Decrease lucene-core JAR size. The core JAR size had increased a lot because of generated code introduced in LUCENE-4161 and LUCENE-3892.
  (Adrien Grand)
2. LUCENE-4317: Improve reuse of internal TokenStreams and StringReader in oal.document.Field.
  (Uwe Schindler, Chris Male, Robert Muir)
3. LUCENE-4327: Support out-of-order scoring in FilteredQuery for higher performance.
  (Mike McCandless, Robert Muir)
4. LUCENE-4364: Optimize MMapDirectory to not make a mapping per-cfs-slice, instead one map per .cfs file. This reduces the total number of maps. Additionally factor out a (package-private) generic ByteBufferIndexInput from MMapDirectory.
  (Uwe Schindler, Robert Muir)
Build (5)
1. LUCENE-4406, LUCENE-4407: Upgrade to randomizedtesting 2.0.1. Workaround for broken test output XMLs due to non-XML text unicode chars in strings. Added printing of failed tests at the end of a test run
  (Dawid Weiss)
2. LUCENE-4252: Detect/Fail tests when they leak RAM in static fields
  (Robert Muir, Dawid Weiss)
3. LUCENE-4360: Support running the same test suite multiple times in parallel
  (Dawid Weiss)
4. LUCENE-3985: Upgrade to randomizedtesting 2.0.0. Added support for thread leak detection. Added support for suite timeouts.
  (Dawid Weiss)
5. LUCENE-4340: Move all non-default codec, postings format and terms dictionary implementations to lucene/codecs.
  (Adrien Grand)
Documentation (1)
1. LUCENE-4302: Fix facet userguide to have HTML loose doctype like all other javadocs.
  (Karl Nicholas via Uwe Schindler)

Release 4.0.0-BETA [2012-08-13]

New features (10)
1. LUCENE-4249: Changed the explanation of the PayloadTermWeight to use the underlying PayloadFunction's explanation as the explanation for the payload score.
  (Scott Smerchek via Robert Muir)
2. LUCENE-4069: Added BloomFilteringPostingsFormat for use with low-frequency terms such as primary keys
  (Mark Harwood, Mike McCandless)
3. LUCENE-4201: Added JapaneseIterationMarkCharFilter to normalize Japanese iteration marks.
  (Robert Muir, Christian Moen)
4. LUCENE-3832: Added BasicAutomata.makeStringUnion method to efficiently create automata from a fixed collection of UTF-8 encoded BytesRef
  (Dawid Weiss, Robert Muir)
5. LUCENE-4153: Added option to fast vector highlighting via BaseFragmentsBuilder to respect field boundaries in the case of highlighting for multivalued fields.
  (Martijn van Groningen)
6. LUCENE-4227: Added DirectPostingsFormat, to hold all postings in memory as uncompressed simple arrays. This uses a tremendous amount of RAM but gives good search performance gains.
  (Mike McCandless)
7. LUCENE-2510, LUCENE-4044: Migrated Solr's Tokenizer-, TokenFilter-, and CharFilterFactories to the lucene-analysis module. The API is still experimental.
  (Chris Male, Robert Muir, Uwe Schindler)
8. LUCENE-4230: When pulling a DocsAndPositionsEnum you can now specify whether or not you require payloads (in addition to offsets); turning one or both off may allow some codec implementations to optimize the enum implementation.
  (Robert Muir, Mike McCandless)
9. LUCENE-4203: Add IndexWriter.tryDeleteDocument(AtomicReader reader, int docID), to attempt deletion by docID as long as the provided reader is an NRT reader, and the segment has not yet been merged away
  (Mike McCandless).
10. LUCENE-4286: Added option to CJKBigramFilter to always also output unigrams. This can be used for a unigram+bigram approach, or at index-time only for better support of short queries.
  (Tom Burton-West, Robert Muir)
API Changes (12)
1. LUCENE-4138: update of morfologik (Polish morphological analyzer) to 1.5.3. The tag attribute class has been renamed to MorphosyntacticTagsAttribute and has a different API (carries a list of tags instead of a compound tag). Upgrade of embedded morfologik dictionaries to version 1.9.
  (Dawid Weiss)
2. LUCENE-4178: set 'tokenized' to true on FieldType by default, so that if you make a custom FieldType and set indexed = true, its analyzed by the analyzer.
  (Robert Muir)
3. LUCENE-4220: Removed the buggy JavaCC-based HTML parser in the benchmark module and replaced by NekoHTML. HTMLParser interface was cleaned up while changing method signatures.
  (Uwe Schindler, Robert Muir)
4. LUCENE-2191: Rename Tokenizer.reset(Reader) to Tokenizer.setReader(Reader). The purpose of this method was always to set a new Reader on the Tokenizer, reusing the object. But the name was often confused with TokenStream.reset().
  (Robert Muir)
5. LUCENE-4228: Refactored CharFilter to extend java.io.FilterReader. CharFilters filter another reader and you override correct() for offset correction.
  (Robert Muir)
6. LUCENE-4240: Analyzer api now just takes fieldName for getOffsetGap. If the field is not analyzed (e.g. StringField), then the analyzer is not invoked at all. If you want to tweak things like positionIncrementGap and offsetGap, analyze the field with KeywordTokenizer instead.
  (Grant Ingersoll, Robert Muir)
7. LUCENE-4250: Pass fieldName to the PayloadFunction explain method, so it parallels with docScore and the default implementation is correct.
  (Robert Muir)
8. LUCENE-3747: Support Unicode 6.1.0.
  (Steve Rowe)
9. LUCENE-3884: Moved ElisionFilter out of org.apache.lucene.analysis.fr package into org.apache.lucene.analysis.util.
  (Robert Muir)
10. LUCENE-4230: When pulling a DocsAndPositionsEnum you now pass an int flags instead of the previous boolean needOffsets. Currently recognized flags are DocsAndPositionsEnum.FLAG_PAYLOADS and DocsAndPositionsEnum.FLAG_OFFSETS
  (Robert Muir, Mike McCandless)
11. LUCENE-4273: When pulling a DocsEnum, you can pass an int flags instead of the previous boolean needsFlags; consistent with the changes for DocsAndPositionsEnum in LUCENE-4230. Currently othe only flag is DocsEnum.FLAG_FREQS.
  (Robert Muir, Mike McCandless)
12. LUCENE-3616: TextField(String, Reader, Store) was reduced to TextField(String, Reader), as the Store parameter didn't make sense: if you supplied Store.YES, you would only receive an exception anyway.
  (Robert Muir)
Optimizations (5)
1. LUCENE-4171: Performance improvements to Packed64.
  (Toke Eskildsen via Adrien Grand)
2. LUCENE-4184: Performance improvements to the aligned packed bits impl.
  (Toke Eskildsen, Adrien Grand)
3. LUCENE-4235: Remove enforcing of Filter rewrite for NRQ queries.
  (Uwe Schindler)
4. LUCENE-4279: Regenerated snowball Stemmers from snowball r554, making them substantially more lightweight. Behavior is unchanged.
  (Robert Muir)
5. LUCENE-4291: Reduced internal buffer size for Jflex-based tokenizers such as StandardTokenizer from 32kb to 8kb.
  (Raintung Li, Steven Rowe, Robert Muir)
Bug Fixes (13)
1. LUCENE-4109: BooleanQueries are not parsed correctly with the flexible query parser.
  (Karsten Rauch via Robert Muir)
2. LUCENE-4176: Fix AnalyzingQueryParser to analyze range endpoints as bytes, so that it works correctly with Analyzers that produce binary non-UTF-8 terms such as CollationAnalyzer.
  (Nattapong Sirilappanich via Robert Muir)
3. LUCENE-4209: Fix FSTCompletionLookup to close its sorter, so that it won't leave temp files behind in /tmp. Fix SortedTermFreqIteratorWrapper to not leave temp files behind in /tmp on Windows. Fix Sort to not leave temp files behind when /tmp is a separate volume.
  (Uwe Schindler, Robert Muir)
4. LUCENE-4221: Fix overeager CheckIndex validation for term vector offsets.
  (Robert Muir)
5. LUCENE-4222: TieredMergePolicy.getFloorSegmentMB was returning the size in bytes not MB
  (Chris Fuller via Mike McCandless)
6. LUCENE-3505: Fix bug (Lucene 4.0alpha only) where boolean conjunctions were sometimes scored incorrectly. Conjunctions of only termqueries where at least one term omitted term frequencies (IndexOptions.DOCS_ONLY) would be scored as if all terms omitted term frequencies.
  (Robert Muir)
7. LUCENE-2686, LUCENE-3505: Fixed BooleanQuery scorers to return correct freq(). Added support for scorer navigation API (Scorer.getChildren) to all queries. Made Scorer.freq() abstract.
  (Koji Sekiguchi, Mike McCandless, Robert Muir)
8. LUCENE-4234: Exception when FacetsCollector is used with ScoreFacetRequest, and the number of matching documents is too large.
  (Gilad Barkai via Shai Erera)
9. LUCENE-4245: Make IndexWriter#close() and MergeScheduler#close() non-interruptible.
  (Mark Miller, Uwe Schindler)
10. LUCENE-4190: restrict allowed filenames that a codec may create to the patterns recognized by IndexFileNames. This also fixes IndexWriter to only delete files matching this pattern from an index directory, to reduce risk when the wrong index path is accidentally passed to IndexWriter
  (Robert Muir, Mike McCandless)
11. LUCENE-4277: Fix IndexWriter deadlock during rollback if flushable DWPT instance are already checked out and queued up but not yet flushed.
  (Simon Willnauer)
12. LUCENE-4282: Automaton FuzzyQuery didnt always deliver all results.
  (Johannes Christen, Uwe Schindler, Robert Muir)
13. LUCENE-4289: Fix minor idf inconsistencies/inefficiencies in highlighter.
  (Robert Muir)
Changes in Runtime Behavior (2)
1. LUCENE-4109: Enable position increments in the flexible queryparser by default.
  (Karsten Rauch via Robert Muir)
2. LUCENE-3616: Field throws exception if you try to set a boost on an unindexed field or one that omits norms.
  (Robert Muir)
Build (7)
1. LUCENE-4094: Support overriding file.encoding on forked test JVMs (force via -Drandomized.file.encoding=XXX).
  (Dawid Weiss)
2. LUCENE-4189: Test output should include timestamps (start/end for each test/ suite). Added -Dtests.timestamps=[off by default].
  (Dawid Weiss)
3. LUCENE-4110: Report long periods of forked jvm inactivity (hung tests/ suites). Added -Dtests.heartbeat=[seconds] with the default of 60 seconds.
  (Dawid Weiss)
4. LUCENE-4160: Added a property to quit the tests after a given number of failures has occurred. This is useful in combination with -Dtests.iters=N (you can start N iterations and wait for M failures, in particular M = 1). -Dtests.maxfailures=M. Alternatively, specify -Dtests.failfast=true to skip all tests after the first failure.
  (Dawid Weiss)
5. LUCENE-4115: JAR resolution/ cleanup should be done automatically for ant clean/ eclipse/ resolve
  (Dawid Weiss)
6. LUCENE-4199, LUCENE-4202, LUCENE-4206: Add a new target "check-forbidden-apis" that parses all generated .class files for use of APIs that use default charset, default locale, or default timezone and fail build if violations found. This ensures, that Lucene / Solr is independent on local configuration options.
  (Uwe Schindler, Robert Muir, Dawid Weiss)
7. LUCENE-4217: Add the possibility to run tests with Atlassian Clover loaded from IVY. A development License solely for Apache code was added in the tools/ folder, but is not included in releases.
  (Uwe Schindler)
Documentation (1)
1. LUCENE-4195: Added package documentation and examples for org.apache.lucene.codecs
  (Alan Woodward via Robert Muir)

Older Releases

Release 4.0.0-ALPHA [2012-07-03]

More information about this release, including any errata related to the release notes, upgrade instructions, or other changes may be found online at: https://wiki.apache.org/lucene-java/Lucene4.0
Changes in backwards compatibility policy (42)
1. LUCENE-1458, LUCENE-2111, LUCENE-2354: Changes from flexible indexing:
  - On upgrading to 4.0, if you do not fully reindex your documents, Lucene will emulate the new flex API on top of the old index, incurring some performance cost (up to ~10% slowdown, typically). To prevent this slowdown, use oal.index.IndexUpgrader to upgrade your indexes to latest file format (LUCENE-3082).
  - The postings APIs (TermEnum, TermDocsEnum, TermPositionsEnum) have been removed in favor of the new flexible indexing (flex) APIs (Fields, FieldsEnum, Terms, TermsEnum, DocsEnum, DocsAndPositionsEnum). One big difference is that field and terms are now enumerated separately: a TermsEnum provides a BytesRef (wraps a byte[]) per term within a single field, not a Term. Another is that when asking for a Docs/AndPositionsEnum, you now specify the skipDocs explicitly (typically this will be the deleted docs, but in general you can provide any Bits).
  - The term vectors APIs (TermFreqVector, TermPositionVector, TermVectorMapper) have been removed in favor of the above flexible indexing APIs, presenting a single-document inverted index of the document from the term vectors.
  - MultiReader ctor now throws IOException
  - Directory.copy/Directory.copyTo now copies all files (not just index files), since what is and isn't and index file is now dependent on the codecs used.
  - UnicodeUtil now uses BytesRef for UTF-8 output, and some method signatures have changed to CharSequence. These are internal APIs and subject to change suddenly.
  - Positional queries (PhraseQuery, *SpanQuery) will now throw an exception if use them on a field that omits positions during indexing (previously they silently returned no results).
  - FieldCache.{Byte,Short,Int,Long,Float,Double}Parser's API has changed -- each parse method now takes a BytesRef instead of a String. If you have an existing Parser, a simple way to fix it is invoke BytesRef.utf8ToString, and pass that String to your existing parser. This will work, but performance would be better if you could fix your parser to instead operate directly on the byte[] in the BytesRef.
  - The internal (experimental) API of NumericUtils changed completely from String to BytesRef. Client code should never use this class, so the change would normally not affect you. If you used some of the methods to inspect terms or create TermQueries out of prefix encoded terms, change to use BytesRef. Please note: Do not use TermQueries to search for single numeric terms. The recommended way is to create a corresponding NumericRangeQuery with upper and lower bound equal and included. TermQueries do not score correct, so the constant score mode of NRQ is the only correct way to handle single value queries.
  - NumericTokenStream now works directly on byte[] terms. If you plug a TokenFilter on top of this stream, you will likely get an IllegalArgumentException, because the NTS does not support TermAttribute/CharTermAttribute. If you want to further filter or attach Payloads to NTS, use the new NumericTermAttribute.
  (Mike McCandless, Robert Muir, Uwe Schindler, Mark Miller, Michael Busch)
2. LUCENE-2858, LUCENE-3733: IndexReader was refactored into abstract AtomicReader, CompositeReader, and DirectoryReader. To open Directory- based indexes use DirectoryReader.open(), the corresponding method in IndexReader is now deprecated for easier migration. Only DirectoryReader supports commits, versions, and reopening with openIfChanged(). Terms, postings, docvalues, and norms can from now on only be retrieved using AtomicReader; DirectoryReader and MultiReader extend CompositeReader, only offering stored fields and access to the sub-readers (which may be composite or atomic). SlowCompositeReaderWrapper (LUCENE-2597) can be used to emulate atomic readers on top of composites. Please review MIGRATE.txt for information how to migrate old code.
  (Uwe Schindler, Robert Muir, Mike McCandless)
3. LUCENE-2265: FuzzyQuery and WildcardQuery now operate on Unicode codepoints, not unicode code units. For example, a Wildcard "?" represents any unicode character. Furthermore, the rest of the automaton package and RegexpQuery use true Unicode codepoint representation.
  (Robert Muir, Mike McCandless)
4. LUCENE-2380: The String-based FieldCache methods (getStrings, getStringIndex) have been replaced with BytesRef-based equivalents (getTerms, getTermsIndex). Also, the sort values (returned in FieldDoc.fields) when sorting by SortField.STRING or SortField.STRING_VAL are now BytesRef instances. See MIGRATE.txt for more details.
  (yonik, Mike McCandless)
5. LUCENE-2480: Though not a change in backwards compatibility policy, pre-3.0 indexes are no longer supported. You should upgrade to 3.x first, then run optimize(), or reindex.
  (Shai Erera, Earwin Burrfoot)
6. LUCENE-2484: Removed deprecated TermAttribute. Use CharTermAttribute and TermToBytesRefAttribute instead.
  (Uwe Schindler)
7. LUCENE-2600: Remove IndexReader.isDeleted in favor of AtomicReader.getDeletedDocs().
  (Mike McCandless)
8. LUCENE-2667: FuzzyQuery's defaults have changed for more performant behavior: the minimum similarity is 2 edit distances from the word, and the priority queue size is 50. To support this, FuzzyQuery now allows specifying unscaled edit distances (foobar~2). If your application depends upon the old defaults of 0.5 (scaled) minimum similarity and Integer.MAX_VALUE priority queue size, you can use FuzzyQuery(Term, float, int, int) to specify those explicitly.
9. LUCENE-2674: MultiTermQuery.TermCollector.collect now accepts the TermsEnum as well.
  (Robert Muir, Mike McCandless)
10. LUCENE-588: WildcardQuery and QueryParser now allows escaping with the '\' character. Previously this was impossible (you could not escape */?, for example). If your code somehow depends on the old behavior, you will need to change it (e.g. using "\\" to escape '\' itself).
  (Sunil Kamath, Terry Yang via Robert Muir)
11. LUCENE-2837: Collapsed Searcher, Searchable into IndexSearcher; removed contrib/remote and MultiSearcher (Mike McCandless); absorbed ParallelMultiSearcher into IndexSearcher as an optional ExecutorServiced passed to its ctor.
  (Mike McCandless)
12. LUCENE-2908, LUCENE-4037: Removed serialization code from lucene classes. It is recommended that you serialize user search needs at a higher level in your application.
  (Robert Muir, Benson Margulies)
13. LUCENE-2831: Changed Weight#scorer, Weight#explain & Filter#getDocIdSet to operate on a AtomicReaderContext instead of directly on IndexReader to enable searches to be aware of IndexSearcher's context.
  (Simon Willnauer)
14. LUCENE-2839: Scorer#score(Collector,int,int) is now public because it is called from other classes and part of public API.
  (Uwe Schindler)
15. LUCENE-2865: Weight#scorer(AtomicReaderContext, boolean, boolean) now accepts a ScorerContext struct instead of booleans.
  (Simon Willnauer)
16. LUCENE-2882: Cut over SpanQuery#getSpans to AtomicReaderContext to enforce per segment semantics on SpanQuery & Spans.
  (Simon Willnauer)
17. LUCENE-2236: Similarity can now be configured on a per-field basis. See the migration notes in MIGRATE.txt for more details.
  (Robert Muir, Doron Cohen)
18. LUCENE-2315: AttributeSource's methods for accessing attributes are now final, else its easy to corrupt the internal states.
  (Uwe Schindler)
19. LUCENE-2814: The IndexWriter.flush method no longer takes "boolean flushDocStores" argument, as we now always flush doc stores (index files holding stored fields and term vectors) while flushing a segment.
  (Mike McCandless)
20. LUCENE-2548: Field names (eg in Term, FieldInfo) are no longer interned.
  (Mike McCandless)
21. LUCENE-2883: The contents of o.a.l.search.function has been consolidated into the queries module and can be found at o.a.l.queries.function. See MIGRATE.txt for more information
  (Chris Male)
22. LUCENE-2392, LUCENE-3299: Decoupled vector space scoring from Query/Weight/Scorer. If you extended Similarity directly before, you should extend TFIDFSimilarity instead. Similarity is now a lower-level API to implement other scoring algorithms. See MIGRATE.txt for more details.
  (David Nemeskey, Simon Willnauer, Mike Mccandless, Robert Muir)
23. LUCENE-3330: The expert visitor API in Scorer has been simplified and extended to support arbitrary relationships. To navigate to a scorer's children, call Scorer.getChildren().
  (Robert Muir)
24. LUCENE-2308: Field is now instantiated with an instance of IndexableFieldType, of which there is a core implementation FieldType. Most properties describing a Field have been moved to IndexableFieldType. See MIGRATE.txt for more details.
  (Nikola Tankovic, Mike McCandless, Chris Male)
25. LUCENE-3396: ReusableAnalyzerBase.TokenStreamComponents.reset(Reader) now returns void instead of boolean. If a Component cannot be reset, it should throw an Exception.
  (Chris Male)
26. LUCENE-3396: ReusableAnalyzerBase has been renamed to Analyzer. All Analyzer implementations must now use Analyzer.TokenStreamComponents, rather than overriding .tokenStream() and .reusableTokenStream() (which are now final).
  (Chris Male)
27. LUCENE-3346: Analyzer.reusableTokenStream() has been renamed to tokenStream() with the old tokenStream() method removed. Consequently it is now mandatory for all Analyzers to support reusability.
  (Chris Male)
28. LUCENE-3473: AtomicReader.getUniqueTermCount() no longer throws UOE when it cannot be easily determined. Instead, it returns -1 to be consistent with this behavior across other index statistics.
  (Robert Muir)
29. LUCENE-1536: The abstract FilteredDocIdSet.match() method is no longer allowed to throw IOException. This change was required to make it conform to the Bits interface. This method should never do I/O for performance reasons.
  (Mike McCandless, Uwe Schindler, Robert Muir, Chris Male, Yonik Seeley, Jason Rutherglen, Paul Elschot)
30. LUCENE-3559: The methods "docFreq" and "maxDoc" on IndexSearcher were removed, as these are no longer used by the scoring system. See MIGRATE.txt for more details.
  (Robert Muir)
31. LUCENE-3533: Removed SpanFilters, they created large lists of objects and did not scale.
  (Robert Muir)
32. LUCENE-3606: IndexReader and subclasses were made read-only. It is no longer possible to delete or undelete documents using IndexReader; you have to use IndexWriter now. As deleting by internal Lucene docID is no longer possible, this requires adding a unique identifier field to your index. Deleting/ relying upon Lucene docIDs is not recommended anyway, because they can change. Consequently commit() was removed and DirectoryReader.open(), openIfChanged() no longer take readOnly booleans or IndexDeletionPolicy instances. Furthermore, IndexReader.setNorm() was removed. If you need customized norm values, the recommended way to do this is by modifying Similarity to use an external byte[] or one of the new DocValues fields (LUCENE-3108). Alternatively, to dynamically change norms (boost *and* length norm) at query time, wrap your AtomicReader using FilterAtomicReader, overriding FilterAtomicReader.norms(). To persist the changes on disk, copy the FilteredIndexReader to a new index using IndexWriter.addIndexes().
  (Uwe Schindler, Robert Muir)
33. LUCENE-3640: Removed IndexSearcher.close(), because IndexSearcher no longer takes a Directory and no longer "manages" IndexReaders, it is a no-op.
  (Robert Muir)
34. LUCENE-3684: Add offsets into DocsAndPositionsEnum, and a few FieldInfo.IndexOption: DOCS_AND_POSITIONS_AND_OFFSETS.
  (Robert Muir, Mike McCandless)
35. LUCENE-2858, LUCENE-3770: FilterIndexReader was renamed to FilterAtomicReader and now extends AtomicReader. If you want to filter composite readers like DirectoryReader or MultiReader, filter their atomic leaves and build a new CompositeReader (e.g. MultiReader) around them.
  (Uwe Schindler, Robert Muir)
36. LUCENE-3736: ParallelReader was split into ParallelAtomicReader and ParallelCompositeReader. Lucene 3.x's ParallelReader is now ParallelAtomicReader; but the new composite variant has improved performance as it works on the atomic subreaders. It requires that all parallel composite readers have the same subreader structure. If you cannot provide this, you can use SlowCompositeReaderWrapper to make all parallel readers atomic and use ParallelAtomicReader.
  (Uwe Schindler, Mike McCandless, Robert Muir)
37. LUCENE-2000: clone() now returns covariant types where possible.
  (ryan)
38. LUCENE-3970: Rename Fields.getUniqueFieldCount -> .size() and Terms.getUniqueTermCount -> .size().
  (Iulius Curt via Mike McCandless)
39. LUCENE-3514: IndexSearcher.setDefaultFieldSortScoring was removed and replaced with per-search control via new expert search methods that take two booleans indicating whether hit scores and max score should be computed.
  (Mike McCandless)
40. LUCENE-4055: You can't put foreign files into the index dir anymore.
41. LUCENE-3866: CompositeReader.getSequentialSubReaders() now returns unmodifiable List<? extends IndexReader>. ReaderUtil.Gather was removed, as IndexReaderContext.leaves() is now the preferred way to access sub-readers.
  (Uwe Schindler)
42. LUCENE-4155: oal.util.ReaderUtil, TwoPhaseCommit, TwoPhaseCommitTool classes were moved to oal.index package. oal.util.CodecUtil class was moved to oal.codecs package. oal.util.DummyConcurrentLock was removed (no longer used in Lucene 4.0).
  (Uwe Schindler)
Changes in Runtime Behavior (11)
1. LUCENE-2846: omitNorms now behaves like omitTermFrequencyAndPositions, if you omitNorms(true) for field "a" for 1000 documents, but then add a document with omitNorms(false) for field "a", all documents for field "a" will have no norms. Previously, Lucene would fill the first 1000 documents with "fake norms" from Similarity.getDefault().
  (Robert Muir, Mike Mccandless)
2. LUCENE-2846: When some documents contain field "a", and others do not, the documents that don't have the field get a norm byte value of 0. Previously, Lucene would populate "fake norms" with Similarity.getDefault() for these documents.
  (Robert Muir, Mike Mccandless)
3. LUCENE-2720: IndexWriter throws IndexFormatTooOldException on open, rather than later when e.g. a merge starts.
  (Shai Erera, Mike McCandless, Uwe Schindler)
4. LUCENE-2881: FieldInfos is now tracked per segment. Before it was tracked per IndexWriter session, which resulted in FieldInfos that had the FieldInfo properties from all previous segments combined. Field numbers are now tracked globally across IndexWriter sessions and persisted into a _X.fnx file on successful commit. The corresponding file format changes are backwards- compatible.
  (Michael Busch, Simon Willnauer)
5. LUCENE-2956, LUCENE-2573, LUCENE-2324, LUCENE-2555: Changes from DocumentsWriterPerThread:
  - IndexWriter now uses a DocumentsWriter per thread when indexing documents. Each DocumentsWriterPerThread indexes documents in its own private segment, and the in memory segments are no longer merged on flush. Instead, each segment is separately flushed to disk and subsequently merged with normal segment merging.
  - DocumentsWriterPerThread (DWPT) is now flushed concurrently based on a FlushPolicy. When a DWPT is flushed, a fresh DWPT is swapped in so that indexing may continue concurrently with flushing. The selected DWPT flushes all its RAM resident documents do disk. Note: Segment flushes don't flush all RAM resident documents but only the documents private to the DWPT selected for flushing.
  - Flushing is now controlled by FlushPolicy that is called for every add, update or delete on IndexWriter. By default DWPTs are flushed either on maxBufferedDocs per DWPT or the global active used memory. Once the active memory exceeds ramBufferSizeMB only the largest DWPT is selected for flushing and the memory used by this DWPT is substracted from the active memory and added to a flushing memory pool, which can lead to temporarily higher memory usage due to ongoing indexing.
  - IndexWriter now can utilize ramBufferSize > 2048 MB. Each DWPT can address up to 2048 MB memory such that the ramBufferSize is now bounded by the max number of DWPT avaliable in the used DocumentsWriterPerThreadPool. IndexWriters net memory consumption can grow far beyond the 2048 MB limit if the application can use all available DWPTs. To prevent a DWPT from exhausting its address space IndexWriter will forcefully flush a DWPT if its hard memory limit is exceeded. The RAMPerThreadHardLimitMB can be controlled via IndexWriterConfig and defaults to 1945 MB. Since IndexWriter flushes DWPT concurrently not all memory is released immediately. Applications should still use a ramBufferSize significantly lower than the JVMs avaliable heap memory since under high load multiple flushing DWPT can consume substantial transient memory when IO performance is slow relative to indexing rate.
  - IndexWriter#commit now doesn't block concurrent indexing while flushing all 'currently' RAM resident documents to disk. Yet, flushes that occur while a a full flush is running are queued and will happen after all DWPT involved in the full flush are done flushing. Applications using multiple threads during indexing and trigger a full flush (eg call commmit() or open a new NRT reader) can use significantly more transient memory.
  - IndexWriter#addDocument and IndexWriter.updateDocument can block indexing threads if the number of active + number of flushing DWPT exceed a safety limit. By default this happens if 2 * max number available thread states (DWPTPool) is exceeded. This safety limit prevents applications from exhausting their available memory if flushing can't keep up with concurrently indexing threads.
  - IndexWriter only applies and flushes deletes if the maxBufferedDelTerms limit is reached during indexing. No segment flushes will be triggered due to this setting.
  - IndexWriter#flush(boolean, boolean) doesn't synchronized on IndexWriter anymore. A dedicated flushLock has been introduced to prevent multiple full- flushes happening concurrently.
  - DocumentsWriter doesn't write shared doc stores anymore.
  (Mike McCandless, Michael Busch, Simon Willnauer)
6. LUCENE-3309: Stored fields no longer record whether they were tokenized or not. In general you should not rely on stored fields to record any "metadata" from indexing (tokenized, omitNorms, IndexOptions, boost, etc.)
  (Mike McCandless)
7. LUCENE-3309: Fast vector highlighter now inserts the MultiValuedSeparator for NOT_ANALYZED fields (in addition to ANALYZED fields). To ensure your offsets are correct you should provide an analyzer that returns 1 from the offsetGap method.
  (Mike McCandless)
8. LUCENE-2621: Removed contrib/instantiated.
  (Robert Muir)
9. LUCENE-1768: StandardQueryTreeBuilder no longer uses RangeQueryNodeBuilder for RangeQueryNodes, since theses two classes were removed; TermRangeQueryNodeProcessor now creates TermRangeQueryNode, instead of RangeQueryNode; the same applies for numeric nodes;
  (Vinicius Barros via Uwe Schindler)
10. LUCENE-3455: QueryParserBase.newFieldQuery() will throw a ParseException if any of the calls to the Analyzer throw an IOException. QueryParseBase.analyzeRangePart() will throw a RuntimException if an IOException is thrown by the Analyzer.
11. LUCENE-4127: IndexWriter will now throw IllegalArgumentException if the first token of an indexed field has 0 positionIncrement (previously it silently corrected it to 1, possibly masking bugs). OffsetAttributeImpl will throw IllegalArgumentException if startOffset is less than endOffset, or if offsets are negative.
  (Robert Muir, Mike McCandless)
API Changes (35)
1. LUCENE-2302, LUCENE-1458, LUCENE-2111, LUCENE-2514: Terms are no longer required to be character based. Lucene views a term as an arbitrary byte[]: during analysis, character-based terms are converted to UTF8 byte[], but analyzers are free to directly create terms as byte[] (NumericField does this, for example). The term data is buffered as byte[] during indexing, written as byte[] into the terms dictionary, and iterated as byte[] (wrapped in a BytesRef) by IndexReader for searching.
2. LUCENE-1458, LUCENE-2111: AtomicReader now directly exposes its deleted docs (getDeletedDocs), providing a new Bits interface to directly query by doc ID.
3. LUCENE-2691: IndexWriter.getReader() has been made package local and is now exposed via open and reopen methods on DirectoryReader. The semantics of the call is the same as it was prior to the API change.
  (Grant Ingersoll, Mike McCandless)
4. LUCENE-2566: QueryParser: Unary operators +,-,! will not be treated as operators if they are followed by whitespace.
  (yonik)
5. LUCENE-2831: Weight#scorer, Weight#explain, Filter#getDocIdSet, Collector#setNextReader & FieldComparator#setNextReader now expect an AtomicReaderContext instead of an IndexReader.
  (Simon Willnauer)
6. LUCENE-2892: Add QueryParser.newFieldQuery (called by getFieldQuery by default) which takes Analyzer as a parameter, for easier customization by subclasses.
  (Robert Muir)
7. LUCENE-2953: In addition to changes in 3.x, PriorityQueue#initialize(int) function was moved into the ctor.
  (Uwe Schindler, Yonik Seeley)
8. LUCENE-3219: SortField type properties have been moved to an enum SortField.Type. In be consistent, CachedArrayCreator.getSortTypeID() has been changed CachedArrayCreator.getSortType().
  (Chris Male)
9. LUCENE-3225: Add TermsEnum.seekExact for faster seeking when you don't need the ceiling term; renamed existing seek methods to either seekCeil or seekExact; changed seekExact(ord) to return no value. Fixed MemoryCodec and SimpleTextCodec to optimize the seekExact case, and fixed places in Lucene to use seekExact when possible.
  (Mike McCandless)
10. LUCENE-1536: Filter.getDocIdSet() now takes an acceptDocs Bits interface (like Scorer) limiting the documents that can appear in the returned DocIdSet. Filters are now required to respect these acceptDocs, otherwise deleted documents may get returned by searches. Most filters will pass these Bits down to DocsEnum, but those, e.g. working on FieldCache, may need to use BitsFilteredDocIdSet.wrap() to exclude them.
  (Mike McCandless, Uwe Schindler, Robert Muir, Chris Male, Yonik Seeley, Jason Rutherglen, Paul Elschot)
11. LUCENE-3722: Similarity methods and collection/term statistics now take long instead of int (to enable distributed scoring of > 2B docs).
  (Yonik Seeley, Andrzej Bialecki, Robert Muir)
12. LUCENE-3761: Generalize SearcherManager into an abstract ReferenceManager. SearcherManager remains a concrete class, but due to the refactoring, the method maybeReopen has been deprecated in favor of maybeRefresh().
  (Shai Erera, Mike McCandless, Simon Willnauer)
13. LUCENE-3859: AtomicReader.hasNorms(field) is deprecated, instead you can inspect the FieldInfo yourself to see if norms are present, which also allows you to get the type.
  (Robert Muir)
14. LUCENE-2606: Changed RegexCapabilities interface to fix thread safety, serialization, and performance problems. If you have written a custom RegexCapabilities it will need to be updated to the new API.
  (Robert Muir, Uwe Schindler)
15. LUCENE-2638 MakeHighFreqTerms.TermStats public to make it more useful for API use.
  (Andrzej Bialecki)
16. LUCENE-2912: The field-specific hashmaps in SweetSpotSimilarity were removed. Instead, use PerFieldSimilarityWrapper to return different SweetSpotSimilaritys for different fields, this way all parameters (such as TF factors) can be customized on a per-field basis.
  (Robert Muir)
17. LUCENE-3308: DuplicateFilter keepMode and processingMode have been converted to enums DuplicateFilter.KeepMode and DuplicateFilter.ProcessingMode repsectively.
18. LUCENE-3483: Move Function grouping collectors from Solr to grouping module.
  (Martijn van Groningen)
19. LUCENE-3606: FieldNormModifier was deprecated, because IndexReader's setNorm() was deprecated. Furthermore, this class is broken, as it does not take position overlaps into account while recalculating norms.
  (Uwe Schindler, Robert Muir)
20. LUCENE-3936: Renamed StringIndexDocValues to DocTermsIndexDocValues.
  (Martijn van Groningen)
21. LUCENE-1768: Deprecated Parametric(Range)QueryNode, RangeQueryNode(Builder), ParametricRangeQueryNodeProcessor were removed.
  (Vinicius Barros via Uwe Schindler)
22. LUCENE-3820: Deprecated constructors accepting pattern matching bounds. The input is buffered and matched in one pass.
  (Dawid Weiss)
23. LUCENE-2413: Deprecated PatternAnalyzer in common/miscellaneous, in favor of the pattern package (CharFilter, Tokenizer, TokenFilter).
  (Robert Muir)
24. LUCENE-2413: Removed the AnalyzerUtil in common/miscellaneous.
  (Robert Muir)
25. LUCENE-1370: Added ShingleFilter option to output unigrams if no shingles can be generated.
  (Chris Harris via Steven Rowe)
26. LUCENE-2514, LUCENE-2551: JDK and ICU CollationKeyAnalyzers were changed to use pure byte keys when Version >= 4.0. This cuts sort key size approximately in half.
  (Robert Muir)
27. LUCENE-3400: Removed DutchAnalyzer.setStemDictionary
  (Chris Male)
28. LUCENE-3431: Removed QueryAutoStopWordAnalyzer.addStopWords* deprecated methods since they prevented reuse. Stopwords are now generated at instantiation through the Analyzer's constructors.
  (Chris Male)
29. LUCENE-3434: Removed ShingleAnalyzerWrapper.set* and PerFieldAnalyzerWrapper.addAnalyzer since they prevent reuse. Both Analyzers should be configured at instantiation.
  (Chris Male)
30. LUCENE-3765: Stopset ctors that previously took Set<?> or Map<?,String> now take CharArraySet and CharArrayMap respectively. Previously the behavior was confusing, and sometimes different depending on the type of set, and ultimately a CharArraySet or CharArrayMap was always used anyway.
  (Robert Muir)
31. LUCENE-3830: Switched to NormalizeCharMap.Builder to create immutable instances of NormalizeCharMap.
  (Dawid Weiss, Mike McCandless)
32. LUCENE-4063: FrenchLightStemmer no longer deletes repeated digits.
  (Tanguy Moal via Steve Rowe)
33. LUCENE-4122: Replace Payload with BytesRef.
  (Andrzej Bialecki)
34. LUCENE-4132: IndexWriter.getConfig() now returns a LiveIndexWriterConfig object which can be used to change the IndexWriter's live settings. IndexWriterConfig is used only for initializing the IndexWriter.
  (Shai Erera)
35. LUCENE-3866: IndexReaderContext.leaves() is now the preferred way to access atomic sub-readers of any kind of IndexReader (for AtomicReaders it returns itself as only leaf with docBase=0).
  (Uwe Schindler)
New features (66)
1. LUCENE-2604: Added RegexpQuery support to QueryParser. Regular expressions are directly supported by the standard queryparser via fieldName:/expression/ OR /expression against default field/ Users who wish to search for literal "/" characters are advised to backslash-escape or quote those characters as needed.
  (Simon Willnauer, Robert Muir)
2. LUCENE-1606, LUCENE-2089: Adds AutomatonQuery, a MultiTermQuery that matches terms against a finite-state machine. Implement WildcardQuery and FuzzyQuery with finite-state methods. Adds RegexpQuery.
  (Robert Muir, Mike McCandless, Uwe Schindler, Mark Miller)
3. LUCENE-3662: Add support for levenshtein distance with transpositions to LevenshteinAutomata, FuzzyTermsEnum, and DirectSpellChecker.
  (Jean-Philippe Barrette-LaPierre, Robert Muir)
4. LUCENE-2321: Cutover to a more RAM efficient packed-ints based representation for the in-memory terms dict index.
  (Mike McCandless)
5. LUCENE-2126: Add new classes for data (de)serialization: DataInput and DataOutput. IndexInput and IndexOutput extend these new classes.
  (Michael Busch)
6. LUCENE-1458, LUCENE-2111: With flexible indexing it is now possible for an application to create its own postings codec, to alter how fields, terms, docs and positions are encoded into the index. The standard codec is the default codec. IndexWriter accepts a Codec class to obtain codecs for newly written segments.
7. LUCENE-1458, LUCENE-2111: Some experimental codecs have been added for flexible indexing, including pulsing codec (inlines low-frequency terms directly into the terms dict, avoiding seeking for some queries), sep codec (stores docs, freqs, positions, skip data and payloads in 5 separate files instead of the 2 used by standard codec), and int block (really a "base" for using block-based compressors like PForDelta for storing postings data).
8. LUCENE-1458, LUCENE-2111: The in-memory terms index used by standard codec is more RAM efficient: terms data is stored as block byte arrays and packed integers. Net RAM reduction for indexes that have many unique terms should be substantial, and initial open time for IndexReaders should be faster. These gains only apply for newly written segments after upgrading.
9. LUCENE-1458, LUCENE-2111: Terms data are now buffered directly as byte[] during indexing, which uses half the RAM for ascii terms (and also numeric fields). This can improve indexing throughput for applications that have many unique terms, since it reduces how often a new segment must be flushed given a fixed RAM buffer size.
10. LUCENE-2489: Added PerFieldCodecWrapper (in oal.index.codecs) which lets you set the Codec per field
  (Mike McCandless)
11. LUCENE-2373: Extend Codec to use SegmentInfosWriter and SegmentInfosReader to allow customization of SegmentInfos data.
  (Andrzej Bialecki)
12. LUCENE-2504: FieldComparator.setNextReader now returns a FieldComparator instance. You can "return this", to just reuse the same instance, or you can return a comparator optimized to the new segment.
  (yonik, Mike McCandless)
13. LUCENE-2648: PackedInts.Iterator now supports to advance by more than a single ordinal.
  (Simon Willnauer)
14. LUCENE-2649: Objects in the FieldCache can optionally store Bits that mark which docs have real values in the native[]
  (ryan)
15. LUCENE-2664: Add SimpleText codec, which stores all terms/postings data in a single text file for transparency (at the expense of poor performance).
  (Sahin Buyrukbilen via Mike McCandless)
16. LUCENE-2589: Add a VariableSizedIntIndexInput, which, when used w/ Sep*, makes it simple to take any variable sized int block coders (like Simple9/16) and use them in a codec.
  (Mike McCandless)
17. LUCENE-2597: Add oal.index.SlowCompositeReaderWrapper, to wrap a composite reader (eg MultiReader or DirectoryReader), making it pretend it's an atomic reader. This is a convenience class (you can use MultiFields static methods directly, instead) if you need to use the flex APIs directly on a composite reader.
  (Mike McCandless)
18. LUCENE-2690: MultiTermQuery boolean rewrites per segment.
  (Uwe Schindler, Robert Muir, Mike McCandless, Simon Willnauer)
19. LUCENE-996: The QueryParser now accepts mixed inclusive and exclusive bounds for range queries. Example: "{3 TO 5]" QueryParser subclasses that overrode getRangeQuery will need to be changed to use the new getRangeQuery method.
  (Andrew Schurman, Mark Miller, yonik)
20. LUCENE-2742: Add native per-field postings format support. Codec lets you now register a postings format for each field and which is in turn recorded into the index. Postings formtas are maintained on a per-segment basis and be resolved without knowing the actual postings format used for writing the segment.
  (Simon Willnauer)
21. LUCENE-2741: Add support for multiple codecs that use the same file extensions within the same segment. Codecs now use their per-segment codec ID in the file names.
  (Simon Willnauer)
22. LUCENE-2843: Added a new terms index impl, VariableGapTermsIndexWriter/Reader, that accepts a pluggable IndexTermSelector for picking which terms should be indexed in the terms dict. This impl stores the indexed terms in an FST, which is much more RAM efficient than FixedGapTermsIndex.
  (Mike McCandless)
23. LUCENE-2862: Added TermsEnum.totalTermFreq() and Terms.getSumTotalTermFreq().
  (Mike McCandless, Robert Muir)
24. LUCENE-3290: Added Terms.getSumDocFreq()
  (Mike McCandless, Robert Muir)
25. LUCENE-3003: Added new expert class oal.index.DocTermsOrd, refactored from Solr's UnInvertedField, for accessing term ords for multi-valued fields, per document. This is similar to FieldCache in that it inverts the index to compute the ords, but differs in that it's able to handle multi-valued fields and does not hold the term bytes in RAM.
  (Mike McCandless)
26. LUCENE-3108, LUCENE-2935, LUCENE-2168, LUCENE-1231: Changes from DocValues (ColumnStrideFields):
  - IndexWriter now supports typesafe dense per-document values stored in a column like storage. DocValues are stored on a per-document basis where each documents field can hold exactly one value of a given type. DocValues are provided via Fieldable and can be used in conjunction with stored and indexed values.
  - DocValues provides an entirely RAM resident document id to value mapping per field as well as a DocIdSetIterator based disk-resident sequential access API relying on filesystem-caches.
  - Both APIs are exposed via IndexReader and the Codec / Flex API allowing expert users to integrate customized DocValues reader and writer implementations by extending existing Codecs.
  - DocValues provides implementations for primitive datatypes like int, long, float, double and arrays of byte. Byte based implementations further provide storage variants like straight or dereferenced stored bytes, fixed and variable length bytes as well as index time sorted based on user-provided comparators.
  (Mike McCandless, Simon Willnauer)
27. LUCENE-3209: Added MemoryCodec, which stores all terms & postings in RAM as an FST; this is good for primary-key fields if you frequently need to lookup by that field or perform deletions against it, for example in a near-real-time setting.
  (Mike McCandless)
28. SOLR-2533: Added support for rewriting Sort and SortFields using an IndexSearcher. SortFields can have SortField.REWRITEABLE type which requires they are rewritten before they are used.
  (Chris Male)
29. LUCENE-3203: FSDirectory can now limit the max allowed write rate (MB/sec) of all running merges, to reduce impact ongoing merging has on searching, NRT reopen time, etc.
  (Mike McCandless)
30. LUCENE-2793: Directory#createOutput & Directory#openInput now accept an IOContext instead of a buffer size to allow low level optimizations for different usecases like merging, flushing and reading.
  (Simon Willnauer, Mike McCandless, Varun Thacker)
31. LUCENE-3354: FieldCache can cache DocTermOrds.
  (Martijn van Groningen)
32. LUCENE-3376: ReusableAnalyzerBase has been moved from modules/analysis/common into lucene/src/java/org/apache/lucene/analysis
  (Chris Male)
33. LUCENE-3423: add Terms.getDocCount(), which returns the number of documents that have at least one term for a field.
  (Yonik Seeley, Robert Muir)
34. LUCENE-2959: Added a variety of different relevance ranking systems to Lucene.
  - Added Okapi BM25, Language Models, Divergence from Randomness, and Information-Based Models. The models are pluggable, support all of lucene's features (boosts, slops, explanations, etc) and queries (spans, etc).
  - All models default to the same index-time norm encoding as DefaultSimilarity, so you can easily try these out/switch back and forth/run experiments and comparisons without reindexing. Note: most of the models do rely upon index statistics that are new in Lucene 4.0, so for existing 3.x indexes its a good idea to upgrade your index to the new format with IndexUpgrader first.
  - Added a new subclass SimilarityBase which provides a simplified API for plugging in new ranking algorithms without dealing with all of the nuances and implementation details of Lucene.
  - For example, to use BM25 for all fields: searcher.setSimilarity(new BM25Similarity());
  If you instead want to apply different similarities (e.g. ones with different parameter values or different algorithms entirely) to different fields, implement PerFieldSimilarityWrapper with your per-field logic.
  (David Mark Nemeskey via Robert Muir)
35. LUCENE-3396: ReusableAnalyzerBase now provides a ReuseStrategy abstraction which controls how TokenStreamComponents are reused per request. Two implementations are provided - GlobalReuseStrategy which implements the current behavior of sharing components between all fields, and PerFieldReuseStrategy which shares per field.
  (Chris Male)
36. LUCENE-2309: Added IndexableField.tokenStream(Analyzer) which is now responsible for creating the TokenStreams for Fields when they are to be indexed.
  (Chris Male)
37. LUCENE-3433: Added random access for non RAM resident IndexDocValues. RAM resident and disk resident IndexDocValues are now exposed via the Source interface. ValuesEnum has been removed in favour of Source.
  (Simon Willnauer)
38. LUCENE-1536: Filters can now be applied down-low, if their DocIdSet implements a new bits() method, returning all documents in a random access way. If the DocIdSet is not too sparse, it will be passed as acceptDocs down to the Scorer as replacement for AtomicReader's live docs. In addition, FilteredQuery backs now IndexSearcher's filtering search methods. Using FilteredQuery you can chain Filters in a very performant way [new FilteredQuery(new FilteredQuery(query, filter1), filter2)], which was not possible with IndexSearcher's methods. FilteredQuery also allows to override the heuristics used to decide if filtering should be done random access or using a conjunction on DocIdSet's iterator().
  (Mike McCandless, Uwe Schindler, Robert Muir, Chris Male, Yonik Seeley, Jason Rutherglen, Paul Elschot)
39. LUCENE-3638: Added sugar methods to IndexReader and IndexSearcher to load only certain fields when loading a document.
  (Peter Chang via Mike McCandless)
40. LUCENE-3628: Norms are represented as DocValues. AtomicReader exposes a #normValues(String) method to obtain norms per field.
  (Simon Willnauer)
41. LUCENE-3687: Similarity#computeNorm(FieldInvertState, Norm) allows to compute norm values or arbitrary precision. Instead of returning a fixed single byte value, custom similarities can now set a integer, float or byte value to the given Norm object.
  (Simon Willnauer)
42. LUCENE-2604, LUCENE-4103: Added RegexpQuery support to contrib/queryparser.
  (Simon Willnauer, Robert Muir, Daniel Truemper)
43. LUCENE-2373: Added a Codec implementation that works with append-only filesystems (such as e.g. Hadoop DFS). SegmentInfos writing/reading code is refactored to support append-only FS, and to allow for future customization of per-segment information.
  (Andrzej Bialecki)
44. LUCENE-2479: Added ability to provide a sort comparator for spelling suggestions along with two implementations. The existing comparator (score, then frequency) is the default
  (Grant Ingersoll)
45. LUCENE-2608: Added the ability to specify the accuracy at method time in the SpellChecker. The per class method is also still available.
  (Grant Ingersoll)
46. LUCENE-2507: Added DirectSpellChecker, which retrieves correction candidates directly from the term dictionary using levenshtein automata.
  (Robert Muir)
47. LUCENE-3527: Add LuceneLevenshteinDistance, which computes string distance in a compatible way as DirectSpellChecker. This can be used to merge top-N results from more than one SpellChecker.
  (James Dyer via Robert Muir)
48. LUCENE-3496: Support grouping by DocValues.
  (Martijn van Groningen)
49. LUCENE-2795: Generified DirectIOLinuxDirectory to work across any unix supporting the O_DIRECT flag when opening a file (tested on Linux and OS X but likely other Unixes will work), and improved it so it can be used for indexing and searching. The directory uses direct IO when doing large merges to avoid unnecessarily evicting cached IO pages due to large merges.
  (Varun Thacker, Mike McCandless)
50. LUCENE-3827: DocsAndPositionsEnum from MemoryIndex implements start/endOffset, if offsets are indexed.
  (Alan Woodward via Mike McCandless)
51. LUCENE-3802, LUCENE-3856: Support for grouped faceting.
  (Martijn van Groningen)
52. LUCENE-3444: Added a second pass grouping collector that keeps track of distinct values for a specified field for the top N group.
  (Martijn van Groningen)
53. LUCENE-3778: Added a grouping utility class that makes it easier to use result grouping for pure Lucene apps.
  (Martijn van Groningen)
54. LUCENE-2341: A new analysis/ filter: Morfologik - a dictionary-driven lemmatizer (accurate stemmer) for Polish (includes morphosyntactic annotations).
  (Michał Dybizbański, Dawid Weiss)
55. LUCENE-2413: Consolidated Lucene/Solr analysis components into analysis/common. New features from Solr now available to Lucene users include:
  - o.a.l.analysis.commongrams: Constructs n-grams for frequently occurring terms and phrases.
  - o.a.l.analysis.charfilter.HTMLStripCharFilter: CharFilter that strips HTML constructs.
  - o.a.l.analysis.miscellaneous.WordDelimiterFilter: TokenFilter that splits words into subwords and performs optional transformations on subword groups.
  - o.a.l.analysis.miscellaneous.RemoveDuplicatesTokenFilter: TokenFilter which filters out Tokens at the same position and Term text as the previous token.
  - o.a.l.analysis.miscellaneous.TrimFilter: Trims leading and trailing whitespace from Tokens in the stream.
  - o.a.l.analysis.miscellaneous.KeepWordFilter: A TokenFilter that only keeps tokens with text contained in the required words (inverse of StopFilter).
  - o.a.l.analysis.miscellaneous.HyphenatedWordsFilter: A TokenFilter that puts hyphenated words broken into two lines back together.
  - o.a.l.analysis.miscellaneous.CapitalizationFilter: A TokenFilter that applies capitalization rules to tokens.
  - o.a.l.analysis.pattern: Package for pattern-based analysis, containing a CharFilter, Tokenizer, and Tokenfilter for transforming text with regexes.
  - o.a.l.analysis.synonym.SynonymFilter: A synonym filter that supports multi-word synonyms.
  - o.a.l.analysis.phonetic: Package for phonetic search, containing various phonetic encoders such as Double Metaphone.
  - o.a.l.analysis.KeywordAnalyzer -> o.a.l.analysis.core.KeywordAnalyzer
  - o.a.l.analysis.KeywordTokenizer -> o.a.l.analysis.core.KeywordTokenizer
  - o.a.l.analysis.LetterTokenizer -> o.a.l.analysis.core.LetterTokenizer
  - o.a.l.analysis.LowerCaseFilter -> o.a.l.analysis.core.LowerCaseFilter
  - o.a.l.analysis.LowerCaseTokenizer -> o.a.l.analysis.core.LowerCaseTokenizer
  - o.a.l.analysis.SimpleAnalyzer -> o.a.l.analysis.core.SimpleAnalyzer
  - o.a.l.analysis.StopAnalyzer -> o.a.l.analysis.core.StopAnalyzer
  - o.a.l.analysis.StopFilter -> o.a.l.analysis.core.StopFilter
  - o.a.l.analysis.WhitespaceAnalyzer -> o.a.l.analysis.core.WhitespaceAnalyzer
  - o.a.l.analysis.WhitespaceTokenizer -> o.a.l.analysis.core.WhitespaceTokenizer
  - o.a.l.analysis.PorterStemFilter -> o.a.l.analysis.en.PorterStemFilter
  - o.a.l.analysis.ASCIIFoldingFilter -> o.a.l.analysis.miscellaneous.ASCIIFoldingFilter
  - o.a.l.analysis.ISOLatin1AccentFilter -> o.a.l.analysis.miscellaneous.ISOLatin1AccentFilter
  - o.a.l.analysis.KeywordMarkerFilter -> o.a.l.analysis.miscellaneous.KeywordMarkerFilter
  - o.a.l.analysis.LengthFilter -> o.a.l.analysis.miscellaneous.LengthFilter
  - o.a.l.analysis.PerFieldAnalyzerWrapper -> o.a.l.analysis.miscellaneous.PerFieldAnalyzerWrapper
  - o.a.l.analysis.TeeSinkTokenFilter -> o.a.l.analysis.sinks.TeeSinkTokenFilter
  - o.a.l.analysis.CharFilter -> o.a.l.analysis.charfilter.CharFilter
  - o.a.l.analysis.BaseCharFilter -> o.a.l.analysis.charfilter.BaseCharFilter
  - o.a.l.analysis.MappingCharFilter -> o.a.l.analysis.charfilter.MappingCharFilter
  - o.a.l.analysis.NormalizeCharMap -> o.a.l.analysis.charfilter.NormalizeCharMap
  - o.a.l.analysis.CharArraySet -> o.a.l.analysis.util.CharArraySet
  - o.a.l.analysis.CharArrayMap -> o.a.l.analysis.util.CharArrayMap
  - o.a.l.analysis.ReusableAnalyzerBase -> o.a.l.analysis.util.ReusableAnalyzerBase
  - o.a.l.analysis.StopwordAnalyzerBase -> o.a.l.analysis.util.StopwordAnalyzerBase
  - o.a.l.analysis.WordListLoader -> o.a.l.analysis.util.WordListLoader
  - o.a.l.analysis.CharTokenizer -> o.a.l.analysis.util.CharTokenizer
  - o.a.l.util.CharacterUtils -> o.a.l.analysis.util.CharacterUtils
  All analyzers in contrib/analyzers and contrib/icu were moved to the analysis/ module. The 'smartcn' and 'stempel' components now depend on 'common'.
  (Chris Male, Robert Muir)
56. LUCENE-4004: Add DisjunctionMaxQuery support to the xml query parser.
  (Benson Margulies via Robert Muir)
57. LUCENE-4025: Add maybeRefreshBlocking to ReferenceManager, to let a caller block until the refresh logic has been executed.
  (Shai Erera, Mike McCandless)
58. LUCENE-4039: Add AddIndexesTask to benchmark, which uses IW.addIndexes.
  (Shai Erera)
59. LUCENE-3514: Added IndexSearcher.searchAfter when Sort is used, returning results after a specified FieldDoc for deep paging.
  (Mike McCandless)
60. LUCENE-4043: Added scoring support via score mode for query time joining.
  (Martijn van Groningen, Mike McCandless)
61. LUCENE-3523: Added oal.search.spell.WordBreakSpellChecker, which generates suggestions by combining two or more terms and/or breaking terms into multiple words. See Javadocs for usage.
  (James Dyer)
62. LUCENE-4019: Added improved parsing of Hunspell Dictionaries so those rules missing the required number of parameters either ignored or cause a ParseException (depending on whether strict parsing is enabled).
  (Luca Cavanna via Chris Male)
63. LUCENE-3440: Add ordered fragments feature with IDF-weighted terms for FVH.
  (Sebastian Lutze via Koji Sekiguchi)
64. LUCENE-4082: Added explain to ToParentBlockJoinQuery.
  (Christoph Kaser, Martijn van Groningen)
65. LUCENE-4108: add replaceTaxonomy to DirectoryTaxonomyWriter, which replaces the taxonomy in place with the given one.
  (Shai Erera)
66. LUCENE-3030: new BlockTree terms dictionary (used by the default Lucene40 postings format) uses less RAM (for the terms index) and disk space (for all terms and metadata) and gives sizable performance gains for terms dictionary intensive operations like FuzzyQuery, direct spell checker and primary-key lookup
  (Mike McCandless).
Optimizations (17)
1. LUCENE-2588: Don't store unnecessary suffixes when writing the terms index, saving RAM in IndexReader; change default terms index interval from 128 to 32, because the terms index now requires much less RAM.
  (Robert Muir, Mike McCandless)
2. LUCENE-2669: Optimize NumericRangeQuery.NumericRangeTermsEnum to not seek backwards when a sub-range has no terms. It now only seeks when the current term is less than the next sub-range's lower end.
  (Uwe Schindler, Mike McCandless)
3. LUCENE-2694: Optimize MultiTermQuery to be single pass for Term lookups. MultiTermQuery now stores TermState per leaf reader during rewrite to re- seek the term dictionary in TermQuery / TermWeight.
  (Simon Willnauer, Mike McCandless, Robert Muir)
4. LUCENE-3292: IndexWriter no longer shares the same SegmentReader instance for merging and NRT readers, which enables directory impls to separately tune IO flags for each.
  (Varun Thacker, Simon Willnauer, Mike McCandless)
5. LUCENE-3328: BooleanQuery now uses a specialized ConjunctionScorer if all boolean clauses are required and instances of TermQuery.
  (Simon Willnauer, Robert Muir)
6. LUCENE-3643: FilteredQuery and IndexSearcher.search(Query, Filter,...) now optimize the special case query instanceof MatchAllDocsQuery to execute as ConstantScoreQuery.
  (Uwe Schindler)
7. LUCENE-3509: Added fasterButMoreRam option for docvalues. This option controls whether the space for packed ints should be rounded up for better performance. This option only applies for docvalues types bytes fixed sorted and bytes var sorted.
  (Simon Willnauer, Martijn van Groningen)
8. LUCENE-3795: Replace contrib/spatial with modules/spatial. This includes a basic spatial strategy interface.
  (David Smiley, Chris Male, ryan)
9. LUCENE-3932: Lucene3x codec loads terms index faster, by pre-allocating the packed ints array based on the .tii file size
  (Sean Bridges via Mike McCandless)
10. LUCENE-3468: Replaced last() and remove() with pollLast() in FirstPassGroupingCollector
  (Martijn van Groningen)
11. LUCENE-3830: Changed MappingCharFilter/NormalizeCharMap to use an FST under the hood, which requires less RAM. NormalizeCharMap no longer accepts empty string match (it did previously, but ignored it).
  (Dawid Weiss, Mike McCandless)
12. LUCENE-4061: improve synchronization in DirectoryTaxonomyWriter.addCategory and few general improvements to DirectoryTaxonomyWriter.
  (Shai Erera, Gilad Barkai)
13. LUCENE-4062: Add new aligned packed bits impls for faster lookup performance; add float acceptableOverheadRatio to getWriter and getMutable API to give packed ints freedom to pick faster implementations
  (Adrien Grand via Mike McCandless)
14. LUCENE-2357: Reduce transient RAM usage when merging segments in IndexWriter.
  (Adrien Grand)
15. LUCENE-4098: Add bulk get/set methods to PackedInts
  (Adrien Grand via Mike McCandless)
16. LUCENE-4156: DirectoryTaxonomyWriter.getSize is no longer synchronized.
  (Shai Erera, Sivan Yogev)
17. LUCENE-4163: Improve concurrency of MMapIndexInput.clone() by using the new WeakIdentityMap on top of a ConcurrentHashMap to manage the cloned instances. WeakIdentityMap was extended to support iterating over its keys.
  (Uwe Schindler)
Bug fixes (19)
1. LUCENE-2803: The FieldCache can miss values if an entry for a reader with more document deletions is requested before a reader with fewer deletions, provided they share some segments.
  (yonik)
2. LUCENE-2645: Fix false assertion error when same token was added one after another with 0 posIncr.
  (David Smiley, Kurosaka Teruhiko via Mike McCandless)
3. LUCENE-3348: Fix thread safety hazards in IndexWriter that could rarely cause deletions to be incorrectly applied.
  (Yonik Seeley, Simon Willnauer, Mike McCandless)
4. LUCENE-3515: Fix terrible merge performance versus 3.x, especially when the directory isn't MMapDirectory, due to failing to reuse DocsAndPositionsEnum while merging
  (Marc Sturlese, Erick Erickson, Robert Muir, Simon Willnauer, Mike McCandless)
5. LUCENE-3589: BytesRef copy(short) didnt set length.
  (Peter Chang via Robert Muir)
6. LUCENE-3045: fixed QueryNodeImpl.containsTag(String key) that was not lowercasing the key before checking for the tag
  (Adriano Crestani)
7. LUCENE-3890: Fixed NPE for grouped faceting on multi-valued fields.
  (Michael McCandless, Martijn van Groningen)
8. LUCENE-2945: Fix hashCode/equals for surround query parser generated queries.
  (Paul Elschot, Simon Rosenthal, gsingers via ehatcher)
9. LUCENE-3971: MappingCharFilter could return invalid final token position.
  (Dawid Weiss, Robert Muir)
10. LUCENE-3820: PatternReplaceCharFilter could return invalid token positions.
  (Dawid Weiss)
11. LUCENE-3969: Throw IAE on bad arguments that could cause confusing errors in CompoundWordTokenFilterBase, PatternTokenizer, PositionFilter, SnowballFilter, PathHierarchyTokenizer, ReversePathHierarchyTokenizer, WikipediaTokenizer, and KeywordTokenizer. ShingleFilter and CommonGramsFilter now populate PositionLengthAttribute. Fixed PathHierarchyTokenizer to reset() all state. Protect against AIOOBE in ReversePathHierarchyTokenizer if skip is large. Fixed wrong final offset calculation in PathHierarchyTokenizer.
  (Mike McCandless, Uwe Schindler, Robert Muir)
12. LUCENE-4060: Fix a synchronization bug in DirectoryTaxonomyWriter.addTaxonomies(). Also, the method has been renamed to addTaxonomy and now takes only one Directory and one OrdinalMap.
  (Shai Erera, Gilad Barkai)
13. LUCENE-3590: Fix AIOOBE in BytesRef/CharsRef copyBytes/copyChars when offset is nonzero, fix off-by-one in CharsRef.subSequence, and fix CharsRef's CharSequence methods to throw exceptions in boundary cases to properly meet the specification.
  (Robert Muir)
14. LUCENE-4084: Attempting to reuse a single IndexWriterConfig instance across more than one IndexWriter resulted in a cryptic exception. This is now fixed, but requires that certain members of IndexWriterConfig (MergePolicy, FlushPolicy, DocumentsWriterThreadPool) implement clone.
  (Robert Muir, Simon Willnauer, Mike McCandless)
15. LUCENE-4079: Fixed loading of Hunspell dictionaries that use aliasing (AF rules)
  (Ludovic Boutros via Chris Male)
16. LUCENE-4077: Expose the max score and per-group scores from ToParentBlockJoinCollector
  (Christoph Kaser, Mike McCandless)
17. LUCENE-4114: Fix int overflow bugs in BYTES_FIXED_STRAIGHT and BYTES_FIXED_DEREF doc values implementations
  (Walt Elder via Mike McCandless).
18. LUCENE-4147: Fixed thread safety issues when rollback() and commit() are called simultaneously.
  (Simon Willnauer, Mike McCandless)
19. LUCENE-4165: Removed closing of the Reader used to read the affix file in HunspellDictionary. Consumers are now responsible for closing all InputStreams once the Dictionary has been instantiated.
  (Torsten Krah, Uwe Schindler, Chris Male)
Documentation (1)
1. LUCENE-3958: Javadocs corrections for IndexWriter.
  (Iulius Curt via Robert Muir)
Build (12)
1. LUCENE-4047: Cleanup of LuceneTestCase: moved blocks of initialization/ cleanup code into JUnit instance and class rules.
  (Dawid Weiss)
2. LUCENE-4016: Require ANT 1.8.2+ for the build.
3. LUCENE-3808: Refactoring of testing infrastructure to use randomizedtesting package: http://labs.carrotsearch.com/randomizedtesting.html
  (Dawid Weiss)
4. LUCENE-3964: Added target stage-maven-artifacts, which stages Maven release artifacts to a Maven staging repository in preparation for release.
  (Steve Rowe)
5. LUCENE-2845: Moved contrib/benchmark to lucene/benchmark.
6. LUCENE-2995: Moved contrib/spellchecker into lucene/suggest.
7. LUCENE-3285: Moved contrib/queryparser into lucene/queryparser
8. LUCENE-3285: Moved contrib/xml-query-parser's demo into lucene/demo
9. LUCENE-3271: Moved contrib/queries BooleanFilter, BoostingQuery, ChainedFilter, FilterClause and TermsFilter into lucene/queries
10. LUCENE-3381: Moved contrib/queries regex.*, DuplicateFilter, FuzzyLikeThisQuery and SlowCollated* into lucene/sandbox. Removed contrib/queries.
11. LUCENE-3286: Moved remainder of contrib/xml-query-parser to lucene/queryparser. Classes now found at org.apache.lucene.queryparser.xml.*
12. LUCENE-4059: Improve ANT task prepare-webpages (used by documentation tasks) to correctly encode build file names as URIs for later processing by XSL.
  (Greg Bowyer, Uwe Schindler)

Release 3.6.1 [2012-07-22]

More information about this release, including any errata related to the release notes, upgrade instructions, or other changes may be found online at: https://wiki.apache.org/lucene-java/Lucene3.6.1
Bug Fixes (6)
1. LUCENE-3969: Throw IAE on bad arguments that could cause confusing errors in KeywordTokenizer.
  (Uwe Schindler, Mike McCandless, Robert Muir)
2. LUCENE-3971: MappingCharFilter could return invalid final token position.
  (Dawid Weiss, Robert Muir)
3. LUCENE-4023: DisjunctionMaxScorer now implements visitSubScorers().
  (Uwe Schindler)
4. LUCENE-2566: + - operators allow any amount of whitespace
  (yonik, janhoy)
5. LUCENE-3590: Fix AIOOBE in BytesRef/CharsRef copyBytes/copyChars when offset is nonzero, fix off-by-one in CharsRef.subSequence, and fix CharsRef's CharSequence methods to throw exceptions in boundary cases to properly meet the specification.
  (Robert Muir)
6. LUCENE-4222: TieredMergePolicy.getFloorSegmentMB was returning the size in bytes not MB
  (Chris Fuller via Mike McCandless)
API Changes (1)
1. LUCENE-4023: Changed the visibility of Scorer#visitSubScorers() to public, otherwise it's impossible to implement Scorers outside the Lucene package.
  (Uwe Schindler)
Optimizations (1)
1. LUCENE-4163: Improve concurrency of MMapIndexInput.clone() by using the new WeakIdentityMap on top of a ConcurrentHashMap to manage the cloned instances. WeakIdentityMap was extended to support iterating over its keys.
  (Uwe Schindler)
Tests (2)
1. LUCENE-3873: add MockGraphTokenFilter, testing analyzers with random graph tokens.
  (Mike McCandless)
2. LUCENE-3968: factor out LookaheadTokenFilter from MockGraphTokenFilter
  (Mike Mccandless)

Release 3.6.0 [2012-04-12]

More information about this release, including any errata related to the release notes, upgrade instructions, or other changes may be found online at: https://wiki.apache.org/lucene-java/Lucene3.6
Changes in backwards compatibility policy (15)
1. LUCENE-3594: The protected inner class (never intended to be visible) FieldCacheTermsFilter.FieldCacheTermsFilterDocIdSet was removed and replaced by another internal implementation.
  (Uwe Schindler)
2. LUCENE-3620: FilterIndexReader now overrides all methods of IndexReader that it should (note that some are still not overridden, as they should be overridden by sub-classes only). In the process, some methods of IndexReader were made final. This is not expected to affect many apps, since these methods already delegate to abstract methods, which you had to already override anyway.
  (Shai Erera)
3. LUCENE-3636: Added SearcherFactory, used by SearcherManager and NRTManager to create new IndexSearchers. You can provide your own implementation to warm new searchers, set an ExecutorService, set a custom Similarity, or even return your own subclass of IndexSearcher. The SearcherWarmer and ExecutorService parameters on these classes were removed, as they are subsumed by SearcherFactory.
  (Shai Erera, Mike McCandless, Robert Muir)
4. LUCENE-3644: The expert ReaderFinishedListener api suffered problems (propagated down to subreaders, but was not called on SegmentReaders, unless they were the owner of the reader core, and other ambiguities). The API is revised: You can set ReaderClosedListeners on any IndexReader, and onClose is called when that reader is closed. SegmentReader has CoreClosedListeners that you can register to know when a shared reader core is closed.
  (Uwe Schindler, Mike McCandless, Robert Muir)
5. LUCENE-3652: The package org.apache.lucene.messages was moved to contrib/queryparser. If you have used those classes in your code just add the lucene-queryparser.jar file to your classpath.
  (Uwe Schindler)
6. LUCENE-3681: FST now stores labels for BYTE2 input type as 2 bytes instead of vInt; this can make FSTs smaller and faster, but it is a break in the binary format so if you had built and saved any FSTs then you need to rebuild them.
  (Robert Muir, Mike McCandless)
7. LUCENE-3679: The expert IndexReader.getFieldNames(FieldOption) API has been removed and replaced with the experimental getFieldInfos API. All IndexReader subclasses must implement getFieldInfos.
  (Mike McCandless)
8. LUCENE-3695: Move confusing add(X) methods out of FST.Builder into FST.Util.
  (Robert Muir, Mike McCandless)
9. LUCENE-3701: Added an additional argument to the expert FST.Builder ctor to take FreezeTail, which you can use to (very-expertly) customize the FST construction process. Pass null if you want the default behavior. Added seekExact() to FSTEnum, and added FST.save/read from a File.
  (Mike McCandless, Dawid Weiss, Robert Muir)
10. LUCENE-3712: Removed unused and untested ReaderUtil#subReader methods.
  (Uwe Schindler)
11. LUCENE-3672: Deprecate Directory.fileModified, IndexCommit.getTimestamp and .getVersion and IndexReader.lastModified and getCurrentVersion
  (Andrzej Bialecki, Robert Muir, Mike McCandless)
12. LUCENE-3760: In IndexReader/DirectoryReader, deprecate static methods getCurrentVersion and getCommitUserData, and non-static method getCommitUserData (use getIndexCommit().getUserData() instead).
  (Ryan McKinley, Robert Muir, Mike McCandless)
13. LUCENE-3867: Deprecate instance creation of RamUsageEstimator, instead the new static method sizeOf(Object) should be used. As the algorithm is now using Hotspot(TM) internals (reference size, header sizes, object alignment), the abstract o.a.l.util.MemoryModel class was completely removed (without replacement). The new static methods no longer support String intern-ness checking, interned strings now count to memory usage as any other Java object.
  (Dawid Weiss, Uwe Schindler, Shai Erera)
14. LUCENE-3738: All readXxx methods in BufferedIndexInput were made final. Subclasses should only override protected readInternal / seekInternal.
  (Uwe Schindler)
15. LUCENE-2599: Deprecated the spatial contrib module, which was buggy and not well maintained. Lucene 4 includes a new spatial module that replaces this.
  (David Smiley, Ryan McKinley, Chris Male)
Changes in Runtime Behavior (3)
1. LUCENE-3796, SOLR-3241: Throw an exception if you try to set an index-time boost on a field that omits norms. Because the index-time boost is multiplied into the norm, previously your boost would be silently discarded.
  (Tomás Fernández Löbbe, Hoss Man, Robert Muir)
2. LUCENE-3848: Fix tokenstreams to not produce a stream with an initial position increment of 0: which is out of bounds (overlapping with a non-existent previous term). Consumers such as IndexWriter and QueryParser still check for and silently correct this situation today, but at some point in the future they may throw an exception.
  (Mike McCandless, Robert Muir)
3. LUCENE-3738: DataInput/DataOutput no longer allow negative vLongs. Negative vInts are still supported (for index backwards compatibility), but should not be used in new code. The read method for negative vLongs was already broken since Lucene 3.1.
  (Uwe Schindler, Mike McCandless, Robert Muir)
Security fixes (1)
1. LUCENE-3588: Try harder to prevent SIGSEGV on cloned MMapIndexInputs: Previous versions of Lucene could SIGSEGV the JVM if you try to access the clone of an IndexInput retrieved from MMapDirectory. This security fix prevents this as best as it can by throwing AlreadyClosedException also on clones.
  (Uwe Schindler, Robert Muir)
API Changes (7)
1. LUCENE-3606: IndexReader will be made read-only in Lucene 4.0, so all methods allowing to delete or undelete documents using IndexReader were deprecated; you should use IndexWriter now. Consequently IndexReader.commit() and all open(), openIfChanged(), clone() methods taking readOnly booleans (or IndexDeletionPolicy instances) were deprecated. IndexReader.setNorm() is superfluous and was deprecated. If you have to change per-document boost use CustomScoreQuery. If you want to dynamically change norms (boost *and* length norm) at query time, wrap your IndexReader using FilterIndexReader, overriding FilterIndexReader.norms(). To persist the changes on disk, copy the FilteredIndexReader to a new index using IndexWriter.addIndexes(). In Lucene 4.0, SimilarityProvider will allow you to customize scoring using external norms, too.
  (Uwe Schindler, Robert Muir)
2. LUCENE-3735: PayloadProcessorProvider was changed to return a ReaderPayloadProcessor instead of DirPayloadProcessor. The selection of the provider to return for the factory is now based on the IndexReader to be merged. To mimic the old behaviour, just use IndexReader.directory() for choosing the provider by Directory.
  (Uwe Schindler)
3. LUCENE-3765: Deprecated StopFilter ctor that took ignoreCase, because in some cases (if the set is a CharArraySet), the argument is ignored. Deprecated StandardAnalyzer and ClassicAnalyzer ctors that take File, please use the Reader ctor instead.
  (Robert Muir)
4. LUCENE-3766: Deprecate no-arg ctors of Tokenizer. Tokenizers are TokenStreams with Readers: tokenizers with null Readers will not be supported in Lucene 4.0, just use a TokenStream.
  (Mike McCandless, Robert Muir)
5. LUCENE-3769: Simplified NRTManager by requiring applyDeletes to be passed to ctor only; if an app needs to mix and match it's free to create two NRTManagers (one always applying deletes and the other never applying deletes).
  (MJB, Shai Erera, Mike McCandless)
6. LUCENE-3761: Generalize SearcherManager into an abstract ReferenceManager. SearcherManager remains a concrete class, but due to the refactoring, the method maybeReopen has been deprecated in favor of maybeRefresh().
  (Shai Erera, Mike McCandless, Simon Willnauer)
7. LUCENE-3776: You now acquire/release the IndexSearcher directly from NRTManager.
  (Mike McCandless)
New Features (11)
1. LUCENE-3593: Added a FieldValueFilter that accepts all documents that either have at least one or no value at all in a specific field.
  (Simon Willnauer, Uwe Schindler, Robert Muir)
2. LUCENE-3586: CheckIndex and IndexUpgrader allow you to specify the specific FSDirectory implementation to use (with the new -dir-impl command-line option).
  (Luca Cavanna via Mike McCandless)
3. LUCENE-3634: IndexReader's static main method was moved to a new tool, CompoundFileExtractor, in contrib/misc.
  (Robert Muir, Mike McCandless)
4. LUCENE-995: The QueryParser now interprets * as an open end for range queries. Literal asterisks may be represented by quoting or escaping (i.e. \* or "*") Custom QueryParser subclasses overriding getRangeQuery() will be passed null for any open endpoint. (Ingo Renner, Adriano Crestani, yonik, Mike McCandless
5. LUCENE-3121: Add sugar reverse lookup (given an output, find the input mapping to it) for FSTs that have strictly monotonic long outputs (such as an ord).
  (Mike McCandless)
6. LUCENE-3671: Add TypeTokenFilter that filters tokens based on their TypeAttribute.
  (Tommaso Teofili via Uwe Schindler)
7. LUCENE-3690,LUCENE-3913: Added HTMLStripCharFilter, a CharFilter that strips HTML markup.
  (Steve Rowe)
8. LUCENE-3725: Added optional packing to FST building; this uses extra RAM during building but results in a smaller FST.
  (Mike McCandless)
9. LUCENE-3714: Add top N shortest cost paths search for FST.
  (Robert Muir, Dawid Weiss, Mike McCandless)
10. LUCENE-3789: Expose MTQ TermsEnum via RewriteMethod for non package private access
  (Simon Willnauer)
11. LUCENE-3881: Added UAX29URLEmailAnalyzer: a standard analyzer that recognizes URLs and emails.
  (Steve Rowe)
Bug fixes (17)
1. LUCENE-3595: Fixed FieldCacheRangeFilter and FieldCacheTermsFilter to correctly respect deletions on reopened SegmentReaders. Factored out FieldCacheDocIdSet to be a top-level class.
  (Uwe Schindler, Simon Willnauer)
2. LUCENE-3627: Don't let an errant 0-byte segments_N file corrupt the index.
  (Ken McCracken via Mike McCandless)
3. LUCENE-3630: The internal method MultiReader.doOpenIfChanged(boolean doClone) was overriding IndexReader.doOpenIfChanged(boolean readOnly), so changing the contract of the overridden method. This method was renamed and made private. In ParallelReader the bug was not existent, but the implementation method was also made private.
  (Uwe Schindler)
4. LUCENE-3641: Fixed MultiReader to correctly propagate readerFinishedListeners to clones/reopened readers.
  (Uwe Schindler)
5. LUCENE-3642, SOLR-2891, LUCENE-3717: Fixed bugs in CharTokenizer, n-gram tokenizers/filters, compound token filters, thai word filter, icutokenizer, pattern analyzer, wikipediatokenizer, and smart chinese where they would create invalid offsets in some situations, leading to problems in highlighting.
  (Max Beutel, Edwin Steiner via Robert Muir)
6. LUCENE-3639: TopDocs.merge was incorrectly setting TopDocs.maxScore to Float.MIN_VALUE when it should be Float.NaN, when there were 0 hits. Improved age calculation in SearcherLifetimeManager, to have double precision and to compute age to be how long ago the searcher was replaced with a new searcher
  (Mike McCandless)
7. LUCENE-3658: Corrected potential concurrency issues with NRTCachingDir, fixed createOutput to overwrite any previous file, and removed invalid asserts
  (Robert Muir, Mike McCandless)
8. LUCENE-3605: don't sleep in a retry loop when trying to locate the segments_N file
  (Robert Muir, Mike McCandless)
9. LUCENE-3711: SentinelIntSet with a small initial size can go into an infinite loop when expanded. This can affect grouping using TermAllGroupsCollector or TermAllGroupHeadsCollector if instantiated with a non default small size.
  (Martijn van Groningen, yonik)
10. LUCENE-3727: When writing stored fields and term vectors, Lucene checks file sizes to detect a bug in some Sun JREs (LUCENE-1282), however, on some NFS filesystems File.length() could be stale, resulting in false errors like "fdx size mismatch while indexing". These checks now use getFilePointer instead to avoid this.
  (Jamir Shaikh, Mike McCandless, Robert Muir)
11. LUCENE-3816: Fixed problem in FilteredDocIdSet, if null was returned from the delegate DocIdSet.iterator(), which is allowed to return null by DocIdSet specification when no documents match.
  (Shay Banon via Uwe Schindler)
12. LUCENE-3821: SloppyPhraseScorer missed documents that ExactPhraseScorer finds When phrase query had repeating terms (e.g. "yes no yes") sloppy query missed documents that exact query matched. Fixed except when for repeating multiterms (e.g. "yes no yes|no").
  (Robert Muir, Doron Cohen)
13. LUCENE-3841: Fix CloseableThreadLocal to also purge stale entries on get(); this fixes certain cases where we were holding onto objects for dead threads for too long
  (Matthew Bellew, Mike McCandless)
14. LUCENE-3872: IndexWriter.close() now throws IllegalStateException if you call it after calling prepareCommit() without calling commit() first.
  (Tim Bogaert via Mike McCandless)
15. LUCENE-3874: Throw IllegalArgumentException from IndexWriter (rather than producing a corrupt index), if a positionIncrement would cause integer overflow. This can happen, for example when using a buggy TokenStream that forgets to call clearAttributes() in combination with a StopFilter.
  (Robert Muir)
16. LUCENE-3876: Fix bug where positions for a document exceeding Integer.MAX_VALUE/2 would produce a corrupt index.
  (Simon Willnauer, Mike Mccandless, Robert Muir)
17. LUCENE-3880: UAX29URLEmailTokenizer now recognizes emails when the mailto: scheme is prepended.
  (Kai Gülzau, Steve Rowe)
Optimizations (1)
1. LUCENE-3653: Improve concurrency in VirtualMethod and AttributeSource by using a WeakIdentityMap based on a ConcurrentHashMap.
  (Uwe Schindler, Gerrit Jansen van Vuuren)
Documentation (2)
1. LUCENE-3597: Fixed incorrect grouping documentation.
  (Martijn van Groningen, Robert Muir)
2. LUCENE-3926: Improve documentation of RAMDirectory, because this class is not intended to work with huge indexes. Everything beyond several hundred megabytes will waste resources (GC cycles), because it uses an internal buffer size of 1024 bytes, producing millions of byte[1024] arrays. This class is optimized for small memory-resident indexes. It also has bad concurrency on multithreaded environments. It is recommended to materialize large indexes on disk and use MMapDirectory, which is a high-performance directory implementation working directly on the file system cache of the operating system, so copying data to Java heap space is not useful.
  (Uwe Schindler, Mike McCandless, Robert Muir)
Build (8)
1. LUCENE-3857: exceptions from other threads in beforeclass/etc do not fail the test
  (Dawid Weiss)
2. LUCENE-3847: LuceneTestCase will now check for modifications of System properties before and after each test (and suite). If changes are detected, the test will fail. A rule can be used to reset system properties to before-scope state (and this has been used to make Solr tests pass).
  (Dawid Weiss, Uwe Schindler).
3. LUCENE-3228: Stop downloading external javadoc package-list files:
  - Added package-list files for Oracle Java javadocs and JUnit javadocs to Lucene/Solr subversion.
  - The Oracle Java javadocs package-list file is excluded from Lucene and Solr source release packages.
  - Regardless of network connectivity, javadocs built from a subversion checkout contain links to Oracle & JUnit javadocs.
  - Building javadocs from a source release package will download the Oracle Java package-list file if it isn't already present.
  - When the Oracle Java package-list file is not present and download fails, the javadocs targets will not fail the build, though an error will appear in the build log. In this case, the built javadocs will not contain links to Oracle Java javadocs.
  - Links from Solr javadocs to Lucene's javadocs are enabled. When building a X.Y.Z-SNAPSHOT version, the links are to the most recently built nightly Jenkins javadocs. When building a release version, links are to the Lucene release javadocs for the same version.
  (Steve Rowe, hossman)
4. LUCENE-3753: Restructure the Lucene build system:
  - Created a new Lucene-internal module named "core" by moving the java/ and test/ directories from lucene/src/ to lucene/core/src/.
  - Eliminated lucene/src/ by moving all its directories up one level.
  - Each internal module (core/, test-framework/, and tools/) now has its own build.xml, from which it is possible to run module-specific targets. lucene/build.xml delegates all build tasks (via <ant dir="internal-module-dir"> calls) to these modules' build.xml files.
  (Steve Rowe)
5. LUCENE-3774: Optimized and streamlined license and notice file validation by refactoring the build task into an ANT task and modifying build scripts to perform top-level checks.
  (Dawid Weiss, Steve Rowe, Robert Muir)
6. LUCENE-3762: Upgrade JUnit to 4.10, refactor state-machine of detecting setUp/tearDown call chaining in LuceneTestCase.
  (Dawid Weiss, Robert Muir)
7. LUCENE-3944: Make the 'generate-maven-artifacts' target use filtered POMs placed under lucene/build/poms/, rather than in each module's base directory. The 'clean' target now removes them.
  (Steve Rowe, Robert Muir)
8. LUCENE-3930: Changed build system to use Apache Ivy for retrival of 3rd party JAR files. Please review BUILD.txt for instructions.
  (Robert Muir, Chris Male, Uwe Schindler, Steven Rowe, Hossman)

Release 3.5.0 [2011-11-27]

Changes in backwards compatibility policy (3)
1. LUCENE-3390: The first approach in Lucene 3.4.0 for missing values support for sorting had a design problem that made the missing value be populated directly into the FieldCache arrays during sorting, leading to concurrency issues. To fix this behaviour, the method signatures had to be changed:
  - FieldCache.getUnValuedDocs() was renamed to FieldCache.getDocsWithField() returning a Bits interface (backported from Lucene 4.0).
  - FieldComparator.setMissingValue() was removed and added to constructor
  As this is expert API, most code will not be affected.
  (Uwe Schindler, Doron Cohen, Mike McCandless)
2. LUCENE-3541: Remove IndexInput's protected copyBuf. If you want to keep a buffer in your IndexInput, do this yourself in your implementation, and be sure to do the right thing on clone()!
  (Robert Muir)
3. LUCENE-2822: TimeLimitingCollector now expects a counter clock instead of relying on a private daemon thread. The global time limiting clock thread has been exposed and is now lazily loaded and fully optional. TimeLimitingCollector now supports setting clock baseline manually to include prelude of a search. Previous versions set the baseline on construction time, now baseline is set once the first IndexReader is passed to the collector unless set before.
  (Simon Willnauer)
Changes in runtime behavior (1)
1. LUCENE-3520: IndexReader.openIfChanged, when passed a near-real-time reader, will now return null if there are no changes. The API has always reserved the right to do this; it's just that in the past for near-real-time readers it never did.
  (Mike McCandless)
Bug fixes (14)
1. LUCENE-3412: SloppyPhraseScorer was returning non-deterministic results for queries with many repeats
  (Doron Cohen)
2. LUCENE-3421: PayloadTermQuery's explain was wrong when includeSpanScore=false.
  (Edward Drapkin via Robert Muir)
3. LUCENE-3432: IndexWriter.expungeDeletes with TieredMergePolicy should ignore the maxMergedSegmentMB setting
  (v.sevel via Mike McCandless)
4. LUCENE-3442: TermQuery.TermWeight.scorer() returns null for non-atomic IndexReaders (optimization bug, introcuced by LUCENE-2829), preventing QueryWrapperFilter and similar classes to get a top-level DocIdSet.
  (Dan C., Uwe Schindler)
5. LUCENE-3390: Corrected handling of missing values when two parallel searches using different missing values for sorting: the missing value was populated directly into the FieldCache arrays during sorting, leading to concurrency issues.
  (Uwe Schindler, Doron Cohen, Mike McCandless)
6. LUCENE-3439: Closing an NRT reader after the writer was closed was incorrectly invoking the DeletionPolicy and (then possibly deleting files) on the closed IndexWriter
  (Robert Muir, Mike McCandless)
7. LUCENE-3215: SloppyPhraseScorer sometimes computed Infinite freq
  (Robert Muir, Doron Cohen)
8. LUCENE-3503: DisjunctionSumScorer would give slightly different scores for a document depending if you used nextDoc() versus advance().
  (Mike McCandless, Robert Muir)
9. LUCENE-3529: Properly support indexing an empty field with empty term text. Previously, if you had assertions enabled you would receive an error during flush, if you didn't, you would get an invalid index.
  (Mike McCandless, Robert Muir)
10. LUCENE-2633: PackedInts Packed32 and Packed64 did not support internal structures larger than 256MB
  (Toke Eskildsen via Mike McCandless)
11. LUCENE-3540: LUCENE-3255 dropped support for pre-1.9 indexes, but the error message in IndexFormatTooOldException was incorrect.
  (Uwe Schindler, Mike McCandless)
12. LUCENE-3541: IndexInput's default copyBytes() implementation was not safe across multiple threads, because all clones shared the same buffer.
  (Robert Muir)
13. LUCENE-3548: Fix CharsRef#append to extend length of the existing char[] and preserve existing chars.
  (Simon Willnauer)
14. LUCENE-3582: Normalize NaN values in NumericUtils.floatToSortableInt() / NumericUtils.doubleToSortableLong(), so this is consistent with stored fields. Also fix NumericRangeQuery to not falsely hit NaNs on half-open ranges (one bound is null). Because of normalization, NumericRangeQuery can now be used to hit NaN values by creating a query with upper == lower == NaN (inclusive).
  (Dawid Weiss, Uwe Schindler)
API Changes (6)
1. LUCENE-3454: Rename IndexWriter.optimize to forceMerge to discourage use of this method since it is horribly costly and rarely justified anymore. MergePolicy.findMergesForOptimize was renamed to findForcedMerges. IndexReader.isOptimized was deprecated. IndexCommit.isOptimized was replaced with getSegmentCount.
  (Robert Muir, Mike McCandless)
2. LUCENE-3205: Deprecated MultiTermQuery.getTotalNumerOfTerms() [and related methods], as the numbers returned are not useful for multi-segment indexes. They were only needed for tests of NumericRangeQuery.
  (Mike McCandless, Uwe Schindler)
3. LUCENE-3574: Deprecate outdated constants in org.apache.lucene.util.Constants and add new ones for Java 6 and Java 7.
  (Uwe Schindler)
4. LUCENE-3571: Deprecate IndexSearcher(Directory). Use the constructors that take IndexReader instead.
  (Robert Muir)
5. LUCENE-3577: Rename IndexWriter.expungeDeletes to forceMergeDeletes, and revamped the javadocs, to discourage use of this method since it is horribly costly and rarely justified. MergePolicy.findMergesToExpungeDeletes was renamed to findForcedDeletesMerges.
  (Robert Muir, Mike McCandless)
6. LUCENE-3464: IndexReader.reopen has been renamed to IndexReader.openIfChanged (a static method), and now returns null (instead of the old reader) if there are no changes in the index, to prevent the common pitfall of accidentally closing the old reader.
New Features (4)
1. LUCENE-3448: Added FixedBitSet.and(other/DISI), andNot(other/DISI).
  (Uwe Schindler)
2. LUCENE-2215: Added IndexSearcher.searchAfter which returns results after a specified ScoreDoc (e.g. last document on the previous page) to support deep paging use cases.
  (Aaron McCurry, Grant Ingersoll, Robert Muir)
3. LUCENE-1990: Adds internal packed ints implementation, to be used for more efficient storage of int arrays when the values are bounded, for example for storing the terms dict index
  (Toke Eskildsen via Mike McCandless)
4. LUCENE-3558: Moved SearcherManager, NRTManager & SearcherLifetimeManager into core. All classes are contained in o.a.l.search.
  (Simon Willnauer)
Optimizations (5)
1. LUCENE-3426: Add NGramPhraseQuery which extends PhraseQuery and tries to reduce the number of terms of the query when rewrite(), in order to improve performance.
  (Robert Muir, Koji Sekiguchi)
2. LUCENE-3494: Optimize FilteredQuery to remove a multiply in score()
  (Uwe Schindler, Robert Muir)
3. LUCENE-3534: Remove filter logic from IndexSearcher and delegate to FilteredQuery's Scorer. This is a partial backport of a cleanup in FilteredQuery/IndexSearcher added by LUCENE-1536 to Lucene 4.0.
  (Uwe Schindler)
4. LUCENE-2205: Very substantial (3-5X) RAM reduction required to hold the terms index on opening an IndexReader
  (Aaron McCurry via Mike McCandless)
5. LUCENE-3443: FieldCache can now set docsWithField, and create an array, in a single pass. This results in faster init time for apps that need both (such as sorting by a field with a missing value).
  (Mike McCandless)
Test Cases (2)
1. LUCENE-3420: Disable the finalness checks in TokenStream and Analyzer for implementing subclasses in different packages, where assertions are not enabled.
  (Uwe Schindler)
2. LUCENE-3506: tests relying on assertions being enabled were no-op because they ignored AssertionError. With this fix now entire test framework (every test) fails if assertions are disabled, unless
  - Dtests.asserts.gracious=true is specified.
    (Doron Cohen)
Build (2)
1. SOLR-2849: Fix dependencies in Maven POMs.
  (David Smiley via Steve Rowe)
2. LUCENE-3561: Fix maven xxx-src.jar files that were missing resources.
  (Uwe Schindler)

Release 3.4.0 [2011-09-14]

Bug fixes (12)
1. LUCENE-3251: Directory#copy failed to close target output if opening the source stream failed.
  (Simon Willnauer)
2. LUCENE-3255: If segments_N file is all zeros (due to file corruption), don't read that to mean the index is empty.
  (Gregory Tarr, Mark Harwood, Simon Willnauer, Mike McCandless)
3. LUCENE-3254: Fixed minor bug in deletes were written to disk, causing the file to sometimes be larger than it needed to be.
  (Mike McCandless)
4. LUCENE-3224: Fixed a big where CheckIndex would incorrectly report a corrupt index if a term with docfreq >= 16 was indexed more than once at the same position.
  (Robert Muir)
5. LUCENE-3339: Fixed deadlock case when multiple threads use the new block-add (IndexWriter.add/updateDocuments) methods.
  (Robert Muir, Mike McCandless)
6. LUCENE-3340: Fixed case where IndexWriter was not flushing at exactly maxBufferedDeleteTerms
  (Mike McCandless)
7. LUCENE-3358, LUCENE-3361: StandardTokenizer and UAX29URLEmailTokenizer wrongly discarded combining marks attached to Han or Hiragana characters, this is fixed if you supply Version >= 3.4 If you supply a previous lucene version, you get the old buggy behavior for backwards compatibility.
  (Trejkaz, Robert Muir)
8. LUCENE-3368: IndexWriter commits segments without applying their buffered deletes when flushing concurrently.
  (Simon Willnauer, Mike McCandless)
9. LUCENE-3365: Create or Append mode determined before obtaining write lock can cause IndexWriter overriding an existing index.
  (Geoff Cooney via Simon Willnauer)
10. LUCENE-3380: Fixed a bug where FileSwitchDirectory's listAll() would wrongly throw NoSuchDirectoryException when all files written so far have been written to one directory, but the other still has not yet been created on the filesystem.
  (Robert Muir)
11. LUCENE-3409: IndexWriter.deleteAll was failing to close pooled NRT SegmentReaders, leading to unused files accumulating in the Directory.
  (tal steier via Mike McCandless)
12. LUCENE-3418: Lucene was failing to fsync index files on commit, meaning an operating system or hardware crash, or power loss, could easily corrupt the index.
  (Mark Miller, Robert Muir, Mike McCandless)
New Features (5)
1. LUCENE-3290: Added FieldInvertState.numUniqueTerms
  (Mike McCandless, Robert Muir)
2. LUCENE-3280: Add FixedBitSet, like OpenBitSet but is not elastic (grow on demand if you set/get/clear too-large indices).
  (Mike McCandless)
3. LUCENE-2048: Added the ability to omit positions but still index term frequencies, you can now control what is indexed into the postings via AbstractField.setIndexOptions: DOCS_ONLY: only documents are indexed: term frequencies and positions are omitted DOCS_AND_FREQS: only documents and term frequencies are indexed: positions are omitted DOCS_AND_FREQS_AND_POSITIONS: full postings: documents, frequencies, and positions AbstractField.setOmitTermFrequenciesAndPositions is deprecated, you should use DOCS_ONLY instead.
  (Robert Muir)
4. LUCENE-3097: Added a new grouping collector that can be used to retrieve all most relevant documents per group. This can be useful in situations when one wants to compute grouping based facets / statistics on the complete query result.
  (Martijn van Groningen)
5. LUCENE-3334: If Java7 is detected, IOUtils.closeSafely() will log suppressed exceptions in the original exception, so stack trace will contain them.
  (Uwe Schindler)
Optimizations (2)
1. LUCENE-3201, LUCENE-3218: CompoundFileSystem code has been consolidated into a Directory implementation. Reading is optimized for MMapDirectory, NIOFSDirectory and SimpleFSDirectory to only map requested parts of the CFS into an IndexInput. Writing to a CFS now tries to append to the CF directly if possible and merges separately written files on the fly instead of during close.
  (Simon Willnauer, Robert Muir)
2. LUCENE-3289: When building an FST you can now tune how aggressively the FST should try to share common suffixes. Typically you can greatly reduce RAM required during building, and CPU consumed, at the cost of a somewhat larger FST.
  (Mike McCandless)
Test Cases (1)
1. LUCENE-3327: Fix AIOOBE when TestFSTs is run with
  - Dtests.verbose=true
    (James Dyer via Mike McCandless)
Build (1)
1. LUCENE-3406: Add ant target 'package-local-src-tgz' to Lucene and Solr to package sources from the local working copy.
  (Seung-Yeoul Yang via Steve Rowe)

Release 3.3.0 [2011-07-01]

Changes in backwards compatibility policy (4)
1. LUCENE-3140: IndexOutput.copyBytes now takes a DataInput (superclass of IndexInput) as its first argument.
  (Robert Muir, Dawid Weiss, Mike McCandless)
2. LUCENE-3191: FieldComparator.value now returns an Object not Comparable; FieldDoc.fields also changed from Comparable[] to Object[]
  (Uwe Schindler, Mike McCandless)
3. LUCENE-3208: Made deprecated methods Query.weight(Searcher) and Searcher.createWeight() final to prevent override. If you have overridden one of these methods, cut over to the non-deprecated implementation.
  (Uwe Schindler, Robert Muir, Yonik Seeley)
4. LUCENE-3238: Made MultiTermQuery.rewrite() final, to prevent problems (such as not properly setting rewrite methods, or not working correctly with things like SpanMultiTermQueryWrapper). To rewrite to a simpler form, instead return a simpler enum from getEnum(IndexReader). For example, to rewrite to a single term, return a SingleTermEnum.
  (ludovic Boutros, Uwe Schindler, Robert Muir)
Changes in runtime behavior (4)
1. LUCENE-2834: the hash used to compute the lock file name when the lock file is not stored in the index has changed. This means you will see a different lucene-XXX-write.lock in your lock directory.
  (Robert Muir, Uwe Schindler, Mike McCandless)
2. LUCENE-3146: IndexReader.setNorm throws IllegalStateException if the field does not store norms.
  (Shai Erera, Mike McCandless)
3. LUCENE-3198: On Linux, if the JRE is 64 bit and supports unmapping, FSDirectory.open now defaults to MMapDirectory instead of NIOFSDirectory since MMapDirectory gives better performance.
  (Mike McCandless)
4. LUCENE-3200: MMapDirectory now uses chunk sizes that are powers of 2. When setting the chunk size, it is rounded down to the next possible value. The new default value for 64 bit platforms is 2^30 (1 GiB), for 32 bit platforms it stays unchanged at 2^28 (256 MiB). Internally, MMapDirectory now only uses one dedicated final IndexInput implementation supporting multiple chunks, which makes Hotspot's life easier.
  (Uwe Schindler, Robert Muir, Mike McCandless)
Bug fixes (7)
1. LUCENE-3147,LUCENE-3152: Fixed open file handles leaks in many places in the code. Now MockDirectoryWrapper (in test-framework) tracks all open files, including locks, and fails if the test fails to release all of them.
  (Mike McCandless, Robert Muir, Shai Erera, Simon Willnauer)
2. LUCENE-3102: CachingCollector.replay was failing to call setScorer per-segment
  (Martijn van Groningen via Mike McCandless)
3. LUCENE-3183: Fix rare corner case where seeking to empty term (field="", term="") with terms index interval 1 could hit ArrayIndexOutOfBoundsException
  (selckin, Robert Muir, Mike McCandless)
4. LUCENE-3208: IndexSearcher had its own private similarity field and corresponding get/setter overriding Searcher's implementation. If you setted a different Similarity instance on IndexSearcher, methods implemented in the superclass Searcher were not using it, leading to strange bugs.
  (Uwe Schindler, Robert Muir)
5. LUCENE-3197: Fix core merge policies to not over-merge during background optimize when documents are still being deleted concurrently with the optimize
  (Mike McCandless)
6. LUCENE-3222: The RAM accounting for buffered delete terms was failing to measure the space required to hold the term's field and text character data.
  (Mike McCandless)
7. LUCENE-3238: Fixed bug where using WildcardQuery("prefix*") inside of a SpanMultiTermQueryWrapper rewrote incorrectly and returned an error instead.
  (ludovic Boutros, Uwe Schindler, Robert Muir)
API Changes (2)
1. LUCENE-3208: Renamed protected IndexSearcher.createWeight() to expert public method IndexSearcher.createNormalizedWeight() as this better describes what this method does. The old method is still there for backwards compatibility. Query.weight() was deprecated and simply delegates to IndexSearcher. Both deprecated methods will be removed in Lucene 4.0.
  (Uwe Schindler, Robert Muir, Yonik Seeley)
2. LUCENE-3197: MergePolicy.findMergesForOptimize now takes Map<SegmentInfo,Boolean> instead of Set<SegmentInfo> as the second argument, so the merge policy knows which segments were originally present vs produced by an optimizing merge
  (Mike McCandless)
Optimizations (1)
1. LUCENE-1736: DateTools.java general improvements.
  (David Smiley via Steve Rowe)
New Features (5)
1. LUCENE-3140: Added experimental FST implementation to Lucene.
  (Robert Muir, Dawid Weiss, Mike McCandless)
2. LUCENE-3193: A new TwoPhaseCommitTool allows running a 2-phase commit algorithm over objects that implement the new TwoPhaseCommit interface (such as IndexWriter).
  (Shai Erera)
3. LUCENE-3191: Added TopDocs.merge, to facilitate merging results from different shards
  (Uwe Schindler, Mike McCandless)
4. LUCENE-3179: Added OpenBitSet.prevSetBit
  (Paul Elschot via Mike McCandless)
5. LUCENE-3210: Made TieredMergePolicy more aggressive in reclaiming segments with deletions; added new methods set/getReclaimDeletesWeight to control this.
  (Mike McCandless)
Build (2)
1. LUCENE-1344: Create OSGi bundle using dev-tools/maven.
  (Nicolas Lalevée, Luca Stancapiano via ryan)
2. LUCENE-3204: The maven-ant-tasks jar is now included in the source tree; users of the generate-maven-artifacts target no longer have to manually place this jar in the Ant classpath. NOTE: when Ant looks for the maven-ant-tasks jar, it looks first in its pre-existing classpath, so any copies it finds will be used instead of the copy included in the Lucene/Solr source tree. For this reason, it is recommeded to remove any copies of the maven-ant-tasks jar in the Ant classpath, e.g. under ~/.ant/lib/ or under the Ant installation's lib/ directory.
  (Steve Rowe)

Release 3.2.0 [2011-06-03]

Changes in backwards compatibility policy (3)
1. LUCENE-2953: PriorityQueue's internal heap was made private, as subclassing with generics can lead to ClassCastException. For advanced use (e.g. in Solr) a method getHeapArray() was added to retrieve the internal heap array as a non-generic Object[].
  (Uwe Schindler, Yonik Seeley)
2. LUCENE-1076: IndexWriter.setInfoStream now throws IOException
  (Mike McCandless, Shai Erera)
3. LUCENE-3084: MergePolicy.OneMerge.segments was changed from SegmentInfos to a List<SegmentInfo>. SegmentInfos itself was changed to no longer extend Vector<SegmentInfo> (to update code that is using Vector-API, use the new asList() and asSet() methods returning unmodifiable collections; modifying SegmentInfos is now only possible through the explicitely declared methods). IndexWriter.segString() now takes Iterable<SegmentInfo> instead of List<SegmentInfo>. A simple recompile should fix this. MergePolicy and SegmentInfos are internal/experimental APIs not covered by the strict backwards compatibility policy.
  (Uwe Schindler, Mike McCandless)
Changes in runtime behavior (2)
1. LUCENE-3065: When a NumericField is retrieved from a Document loaded from IndexReader (or IndexSearcher), it will now come back as NumericField not as a Field with a string-ified version of the numeric value you had indexed. Note that this only applies for newly-indexed Documents; older indices will still return Field with the string-ified numeric value. If you call Document.get(), the value comes still back as String, but Document.getFieldable() returns NumericField instances.
  (Uwe Schindler, Ryan McKinley, Mike McCandless)
2. LUCENE-1076: Changed the default merge policy from LogByteSizeMergePolicy to TieredMergePolicy, as of Version.LUCENE_32 (passed to IndexWriterConfig), which is able to merge non-contiguous segments. This means docIDs no longer necessarily stay "in order" during indexing. If this is a problem then you can use either of the LogMergePolicy impls.
  (Mike McCandless)
New features (5)
1. LUCENE-3082: Added index upgrade tool oal.index.IndexUpgrader that allows to upgrade all segments to last recent supported index format without fully optimizing.
  (Uwe Schindler, Mike McCandless)
2. LUCENE-1076: Added TieredMergePolicy which is able to merge non-contiguous segments, which means docIDs no longer necessarily stay "in order".
  (Mike McCandless, Shai Erera)
3. LUCENE-3071: Adding ReversePathHierarchyTokenizer, added skip parameter to PathHierarchyTokenizer
  (Olivier Favre via ryan)
4. LUCENE-1421, LUCENE-3102: added CachingCollector which allow you to cache document IDs and scores encountered during the search, and "replay" them to another Collector.
  (Mike McCandless, Shai Erera)
5. LUCENE-3112: Added experimental IndexWriter.add/updateDocuments, enabling a block of documents to be indexed, atomically, with guaranteed sequential docIDs.
  (Mike McCandless)
API Changes (3)
1. LUCENE-3061: IndexWriter's getNextMerge() and merge(OneMerge) are now public (though @lucene.experimental), allowing for custom MergeScheduler implementations.
  (Shai Erera)
2. LUCENE-3065: Document.getField() was deprecated, as it throws ClassCastException when loading lazy fields or NumericFields.
  (Uwe Schindler, Ryan McKinley, Mike McCandless)
3. LUCENE-2027: Directory.touchFile is deprecated and will be removed in 4.0.
  (Mike McCandless)
Optimizations (3)
1. LUCENE-2990: ArrayUtil/CollectionUtil.*Sort() methods now exit early on empty or one-element lists/arrays.
  (Uwe Schindler)
2. LUCENE-2897: Apply deleted terms while flushing a segment. We still buffer deleted terms to later apply to past segments.
  (Mike McCandless)
3. LUCENE-3126: IndexWriter.addIndexes copies incoming segments into CFS if they aren't already and MergePolicy allows that.
  (Shai Erera)
Bug fixes (6)
1. LUCENE-2996: addIndexes(IndexReader) did not flush before adding the new indexes, causing existing deletions to be applied on the incoming indexes as well.
  (Shai Erera, Mike McCandless)
2. LUCENE-3024: Index with more than 2.1B terms was hitting AIOOBE when seeking TermEnum (eg used by Solr's faceting)
  (Tom Burton-West, Mike McCandless)
3. LUCENE-3042: When a filter or consumer added Attributes to a TokenStream chain after it was already (partly) consumed [or clearAttributes(), captureState(), cloneAttributes(),... was called by the Tokenizer], the Tokenizer calling clearAttributes() or capturing state after addition may not do this on the newly added Attribute. This bug affected only very special use cases of the TokenStream-API, most users would not have recognized it.
  (Uwe Schindler, Robert Muir)
4. LUCENE-3054: PhraseQuery can in some cases stack overflow in SorterTemplate.quickSort(). This fix also adds an optimization to PhraseQuery as term with lower doc freq will also have less positions.
  (Uwe Schindler, Robert Muir, Otis Gospodnetic)
5. LUCENE-3068: sloppy phrase query failed to match valid documents when multiple query terms had same position in the query.
  (Doron Cohen)
6. LUCENE-3012: Lucene writes the header now for separate norm files (*.sNNN)
  (Robert Muir)
Build (2)
1. LUCENE-3006: Building javadocs will fail on warnings by default. Override with -Dfailonjavadocwarning=false
  (sarowe, gsingers)
2. LUCENE-3128: "ant eclipse" creates a .project file for easier Eclipse integration (unless one already exists).
  (Daniel Serodio via Shai Erera)
Test Cases (1)
1. LUCENE-3002: added 'tests.iter.min' to control 'tests.iter' by allowing to stop iterating if at least 'tests.iter.min' ran and a failure occured.
  (Shai Erera, Chris Hostetter)

Release 3.1.0 [2011-03-31]

Changes in backwards compatibility policy (18)
1. LUCENE-2719: Changed API of internal utility class org.apache.lucene.util.SorterTemplate to support faster quickSort using pivot values and also merge sort and insertion sort. If you have used this class, you have to implement two more methods for handling pivots.
  (Uwe Schindler, Robert Muir, Mike McCandless)
2. LUCENE-1923: Renamed SegmentInfo & SegmentInfos segString method to toString. These are advanced APIs and subject to change suddenly.
  (Tim Smith via Mike McCandless)
3. LUCENE-2190: Removed deprecated customScore() and customExplain() methods from experimental CustomScoreQuery.
  (Uwe Schindler)
4. LUCENE-2286: Enabled DefaultSimilarity.setDiscountOverlaps by default. This means that terms with a position increment gap of zero do not affect the norms calculation by default.
  (Robert Muir)
5. LUCENE-2320: MergePolicy.writer is now of type SetOnce, which allows setting the IndexWriter for a MergePolicy exactly once. You can change references to 'writer' from writer.doXYZ() to writer.get().doXYZ() (it is also advisable to add an assert writer != null; before you access the wrapped IndexWriter.)
  In addition, MergePolicy only exposes a default constructor, and the one that took IndexWriter as argument has been removed from all MergePolicy extensions.
  (Shai Erera via Mike McCandless)
6. LUCENE-2328: SimpleFSDirectory.SimpleFSIndexInput is moved to FSDirectory.FSIndexInput. Anyone extending this class will have to fix their code on upgrading.
  (Earwin Burrfoot via Mike McCandless)
7. LUCENE-2302: The new interface for term attributes, CharTermAttribute, now implements CharSequence. This requires the toString() methods of CharTermAttribute, deprecated TermAttribute, and Token to return only the term text and no other attribute contents. LUCENE-2374 implements an attribute reflection API to no longer rely on toString() for attribute inspection.
  (Uwe Schindler, Robert Muir)
8. LUCENE-2372, LUCENE-2389: StandardAnalyzer, KeywordAnalyzer, PerFieldAnalyzerWrapper, WhitespaceTokenizer are now final. Also removed the now obsolete and deprecated Analyzer.setOverridesTokenStreamMethod(). Analyzer and TokenStream base classes now have an assertion in their ctor, that check subclasses to be final or at least have final implementations of incrementToken(), tokenStream(), and reusableTokenStream().
  (Uwe Schindler, Robert Muir)
9. LUCENE-2316: Directory.fileLength contract was clarified - it returns the actual file's length if the file exists, and throws FileNotFoundException otherwise. Returning length=0 for a non-existent file is no longer allowed. If you relied on that, make sure to catch the exception.
  (Shai Erera)
10. LUCENE-2386: IndexWriter no longer performs an empty commit upon new index creation. Previously, if you passed an empty Directory and set OpenMode to CREATE*, IndexWriter would make a first empty commit. If you need that behavior you can call writer.commit()/close() immediately after you create it.
  (Shai Erera, Mike McCandless)
11. LUCENE-2733: Removed public constructors of utility classes with only static methods to prevent instantiation.
  (Uwe Schindler)
12. LUCENE-2602: The default (LogByteSizeMergePolicy) merge policy now takes deletions into account by default. You can disable this by calling setCalibrateSizeByDeletes(false) on the merge policy.
  (Mike McCandless)
13. LUCENE-2529, LUCENE-2668: Position increment gap and offset gap of empty values in multi-valued field has been changed for some cases in index. If you index empty fields and uses positions/offsets information on that fields, reindex is recommended.
  (David Smiley, Koji Sekiguchi)
14. LUCENE-2804: Directory.setLockFactory new declares throwing an IOException.
  (Shai Erera, Robert Muir)
15. LUCENE-2837: Added deprecations noting that in 4.0, Searcher and Searchable are collapsed into IndexSearcher; contrib/remote and MultiSearcher have been removed.
  (Mike McCandless)
16. LUCENE-2854: Deprecated SimilarityDelegator and Similarity.lengthNorm; the latter is now final, forcing any custom Similarity impls to cutover to the more general computeNorm
  (Robert Muir, Mike McCandless)
17. LUCENE-2869: Deprecated Query.getSimilarity: instead of using "runtime" subclassing/delegation, subclass the Weight instead.
  (Robert Muir)
18. LUCENE-2674: A new idfExplain method was added to Similarity, that accepts an incoming docFreq. If you subclass Similarity, make sure you also override this method on upgrade.
  (Robert Muir, Mike McCandless)
Changes in runtime behavior (13)
1. LUCENE-1923: Made IndexReader.toString() produce something meaningful
  (Tim Smith via Mike McCandless)
2. LUCENE-2179: CharArraySet.clear() is now functional.
  (Robert Muir, Uwe Schindler)
3. LUCENE-2455: IndexWriter.addIndexes no longer optimizes the target index before it adds the new ones. Also, the existing segments are not merged and so the index will not end up with a single segment (unless it was empty before). In addition, addIndexesNoOptimize was renamed to addIndexes and no longer invokes a merge on the incoming and target segments, but instead copies the segments to the target index. You can call maybeMerge or optimize after this method completes, if you need to.
  In addition, Directory.copyTo* were removed in favor of copy which takes the target Directory, source and target files as arguments, and copies the source file to the target Directory under the target file name.
  (Shai Erera)
4. LUCENE-2663: IndexWriter no longer forcefully clears any existing locks when create=true. This was a holdover from when SimpleFSLockFactory was the default locking implementation, and, even then it was dangerous since it could mask bugs in IndexWriter's usage, allowing applications to accidentally open two writers on the same directory.
  (Mike McCandless)
5. LUCENE-2701: maxMergeMBForOptimize and maxMergeDocs constraints set on LogMergePolicy now affect optimize() as well (as opposed to only regular merges). This means that you can run optimize() and too large segments won't be merged.
  (Shai Erera)
6. LUCENE-2753: IndexReader and DirectoryReader .listCommits() now return a List, guaranteeing the commits are sorted from oldest to latest.
  (Shai Erera)
7. LUCENE-2785: TopScoreDocCollector, TopFieldCollector and the IndexSearcher search methods that take an int nDocs will now throw IllegalArgumentException if nDocs is 0. Instead, you should use the newly added TotalHitCountCollector.
  (Mike McCandless)
8. LUCENE-2790: LogMergePolicy.useCompoundFile's logic now factors in noCFSRatio to determine whether the passed in segment should be compound.
  (Shai Erera, Earwin Burrfoot)
9. LUCENE-2805: IndexWriter now increments the index version on every change to the index instead of for every commit. Committing or closing the IndexWriter without any changes to the index will not cause any index version increment.
  (Simon Willnauer, Mike McCandless)
10. LUCENE-2650, LUCENE-2825: The behavior of FSDirectory.open has changed. On 64-bit Windows and Solaris systems that support unmapping, FSDirectory.open returns MMapDirectory. Additionally the behavior of MMapDirectory has been changed to enable unmapping by default if supported by the JRE.
  (Mike McCandless, Uwe Schindler, Robert Muir)
11. LUCENE-2829: Improve the performance of "primary key" lookup use case (running a TermQuery that matches one document) on a multi-segment index.
  (Robert Muir, Mike McCandless)
12. LUCENE-2010: Segments with 100% deleted documents are now removed on IndexReader or IndexWriter commit.
  (Uwe Schindler, Mike McCandless)
13. LUCENE-2960: Allow some changes to IndexWriterConfig to take effect "live" (after an IW is instantiated), via IndexWriter.getConfig().setXXX(...)
  (Shay Banon, Mike McCandless)
API Changes (26)
1. LUCENE-2076: Rename FSDirectory.getFile -> getDirectory.
  (George Aroush via Mike McCandless)
2. LUCENE-1260: Change norm encode (float->byte) and decode (byte->float) to be instance methods not static methods. This way a custom Similarity can alter how norms are encoded, though they must still be encoded as a single byte
  (Johan Kindgren via Mike McCandless)
3. LUCENE-2103: NoLockFactory should have a private constructor; until Lucene 4.0 the default one will be deprecated.
  (Shai Erera via Uwe Schindler)
4. LUCENE-2177: Deprecate the Field ctors that take byte[] and Store. Since the removal of compressed fields, Store can only be YES, so it's not necessary to specify.
  (Erik Hatcher via Mike McCandless)
5. LUCENE-2200: Several final classes had non-overriding protected members. These were converted to private and unused protected constructors removed.
  (Steven Rowe via Robert Muir)
6. LUCENE-2240: SimpleAnalyzer and WhitespaceAnalyzer now have Version ctors.
  (Simon Willnauer via Uwe Schindler)
7. LUCENE-2259: Add IndexWriter.deleteUnusedFiles, to attempt removing unused files. This is only useful on Windows, which prevents deletion of open files. IndexWriter will eventually remove these files itself; this method just lets you do so when you know the files are no longer open by IndexReaders.
  (luocanrao via Mike McCandless)
8. LUCENE-2282: IndexFileNames is exposed as a public class allowing for easier use by external code. In addition it offers a matchExtension method which callers can use to query whether a certain file matches a certain extension.
  (Shai Erera via Mike McCandless)
9. LUCENE-124: Add a TopTermsBoostOnlyBooleanQueryRewrite to MultiTermQuery. This rewrite method is similar to TopTermsScoringBooleanQueryRewrite, but only scores terms by their boost values. For example, this can be used with FuzzyQuery to ensure that exact matches are always scored higher, because only the boost will be used in scoring.
  (Robert Muir)
10. LUCENE-2015: Add a static method foldToASCII to ASCIIFoldingFilter to expose its folding logic.
  (Cédrik Lime via Robert Muir)
11. LUCENE-2294: IndexWriter constructors have been deprecated in favor of a single ctor which accepts IndexWriterConfig and a Directory. You can set all the parameters related to IndexWriter on IndexWriterConfig. The different setter/getter methods were deprecated as well. One should call writer.getConfig().getXYZ() to query for a parameter XYZ. Additionally, the setter/getter related to MergePolicy were deprecated as well. One should interact with the MergePolicy directly.
  (Shai Erera via Mike McCandless)
12. LUCENE-2320: IndexWriter's MergePolicy configuration was moved to IndexWriterConfig and the respective methods on IndexWriter were deprecated.
  (Shai Erera via Mike McCandless)
13. LUCENE-2328: Directory now keeps track itself of the files that are written but not yet fsynced. The old Directory.sync(String file) method is deprecated and replaced with Directory.sync(Collection<String> files). Take a look at FSDirectory to see a sample of how such tracking might look like, if needed in your custom Directories.
  (Earwin Burrfoot via Mike McCandless)
14. LUCENE-2302: Deprecated TermAttribute and replaced by a new CharTermAttribute. The change is backwards compatible, so mixed new/old TokenStreams all work on the same char[] buffer independent of which interface they use. CharTermAttribute has shorter method names and implements CharSequence and Appendable. This allows usage like Java's StringBuilder in addition to direct char[] access. Also terms can directly be used in places where CharSequence is allowed (e.g. regular expressions).
  (Uwe Schindler, Robert Muir)
15. LUCENE-2402: IndexWriter.deleteUnusedFiles now deletes unreferenced commit points too. If you use an IndexDeletionPolicy which holds onto index commits (such as SnapshotDeletionPolicy), you can call this method to remove those commit points when they are not needed anymore (instead of waiting for the next commit).
  (Shai Erera)
16. LUCENE-2481: SnapshotDeletionPolicy.snapshot() and release() were replaced with equivalent ones that take a String (id) as argument. You can pass whatever ID you want, as long as you use the same one when calling both.
  (Shai Erera)
17. LUCENE-2356: Add IndexWriterConfig.set/getReaderTermIndexDivisor, to set what IndexWriter passes for termsIndexDivisor to the readers it opens internally when apply deletions or creating a near-real-time reader.
  (Earwin Burrfoot via Mike McCandless)
18. LUCENE-2167,LUCENE-2699,LUCENE-2763,LUCENE-2847: StandardTokenizer/Analyzer in common/standard/ now implement the Word Break rules from the Unicode 6.0.0 Text Segmentation algorithm (UAX#29), covering the full range of Unicode code points, including values from U+FFFF to U+10FFFF
  ClassicTokenizer/Analyzer retains the old (pre-Lucene 3.1) StandardTokenizer/ Analyzer implementation and behavior. Only the Unicode Basic Multilingual Plane (code points from U+0000 to U+FFFF) is covered.
  UAX29URLEmailTokenizer tokenizes URLs and E-mail addresses according to the relevant RFCs, in addition to implementing the UAX#29 Word Break rules.
  (Steven Rowe, Robert Muir, Uwe Schindler)
19. LUCENE-2778: RAMDirectory now exposes newRAMFile() which allows to override and return a different RAMFile implementation.
  (Shai Erera)
20. LUCENE-2785: Added TotalHitCountCollector whose sole purpose is to count the number of hits matching the query.
  (Mike McCandless)
21. LUCENE-2846: Deprecated IndexReader.setNorm(int, String, float). This method is only syntactic sugar for setNorm(int, String, byte), but using the global Similarity.getDefault().encodeNormValue(). Use the byte-based method instead to ensure that the norm is encoded with your Similarity.
  (Robert Muir, Mike McCandless)
22. LUCENE-2374: Added Attribute reflection API: It's now possible to inspect the contents of AttributeImpl and AttributeSource using a well-defined API. This is e.g. used by Solr's AnalysisRequestHandlers to display all attributes in a structured way. There are also some backwards incompatible changes in toString() output, as LUCENE-2302 introduced the CharSequence interface to CharTermAttribute leading to changed toString() return values. The new API allows to get a string representation in a well-defined way using a new method reflectAsString(). For backwards compatibility reasons, when toString() was implemented by implementation subclasses, the default implementation of AttributeImpl.reflectWith() uses toString()s output instead to report the Attribute's properties. Otherwise, reflectWith() uses Java's reflection (like toString() did before) to get the attribute properties. In addition, the mandatory equals() and hashCode() are no longer required for AttributeImpls, but can still be provided (if needed).
  (Uwe Schindler)
23. LUCENE-2691: Deprecate IndexWriter.getReader in favor of IndexReader.open(IndexWriter)
  (Grant Ingersoll, Mike McCandless)
24. LUCENE-2876: Deprecated Scorer.getSimilarity(). If your Scorer uses a Similarity, it should keep it itself. Fixed Scorers to pass their parent Weight, so that Scorer.visitSubScorers (LUCENE-2590) will work correctly.
  (Robert Muir, Doron Cohen)
25. LUCENE-2900: When opening a near-real-time (NRT) reader (IndexReader.re/open(IndexWriter)) you can now specify whether deletes should be applied. Applying deletes can be costly, and some expert use cases can handle seeing deleted documents returned. The deletes remain buffered so that the next time you open an NRT reader and pass true, all deletes will be a applied.
  (Mike McCandless)
26. LUCENE-1253: LengthFilter (and Solr's KeepWordTokenFilter) now require up front specification of enablePositionIncrement. Together with StopFilter they have a common base class (FilteringTokenFilter) that handles the position increments automatically. Implementors only need to override an accept() method that filters tokens.
  (Uwe Schindler, Robert Muir)
Bug fixes (23)
1. LUCENE-2249: ParallelMultiSearcher should shut down thread pool on close.
  (Martin Traverso via Uwe Schindler)
2. LUCENE-2273: FieldCacheImpl.getCacheEntries() used WeakHashMap incorrectly and lead to ConcurrentModificationException.
  (Uwe Schindler, Robert Muir)
3. LUCENE-2328: Index files fsync tracking moved from IndexWriter/IndexReader to Directory, and it no longer leaks memory.
  (Earwin Burrfoot via Mike McCandless)
4. LUCENE-2074: Reduce buffer size of lexer back to default on reset.
  (Ruben Laguna, Shai Erera via Uwe Schindler)
5. LUCENE-2496: Don't throw NPE if IndexWriter is opened with CREATE on a prior (corrupt) index missing its segments_N file.
  (Mike McCandless)
6. LUCENE-2458: QueryParser no longer automatically forms phrase queries, assuming whitespace tokenization. Previously all CJK queries, for example, would be turned into phrase queries. The old behavior is preserved with the matchVersion parameter for previous versions. Additionally, you can explicitly enable the old behavior with setAutoGeneratePhraseQueries(true)
  (Robert Muir)
7. LUCENE-2537: FSDirectory.copy() implementation was unsafe and could result in OOM if a large file was copied.
  (Shai Erera)
8. LUCENE-2580: MultiPhraseQuery throws AIOOBE if number of positions exceeds number of terms at one position
  (Jayendra Patil via Mike McCandless)
9. LUCENE-2617: Optional clauses of a BooleanQuery were not factored into coord if the scorer for that segment returned null. This can cause the same document to score to differently depending on what segment it resides in.
  (yonik)
10. LUCENE-2272: Fix explain in PayloadNearQuery and also fix scoring issue
  (Peter Keegan via Grant Ingersoll)
11. LUCENE-2732: Fix charset problems in XML loading in HyphenationCompoundWordTokenFilter.
  (Uwe Schindler)
12. LUCENE-2802: NRT DirectoryReader returned incorrect values from getVersion, isOptimized, getCommitUserData, getIndexCommit and isCurrent due to a mutable reference to the IndexWriters SegmentInfos.
  (Simon Willnauer, Earwin Burrfoot)
13. LUCENE-2852: Fixed corner case in RAMInputStream that would hit a false EOF after seeking to EOF then seeking back to same block you were just in and then calling readBytes
  (Robert Muir, Mike McCandless)
14. LUCENE-2860: Fixed SegmentInfo.sizeInBytes to factor includeDocStores when it decides whether to return the cached computed size or not.
  (Shai Erera)
15. LUCENE-2584: SegmentInfo.files() could hit ConcurrentModificationException if called by multiple threads.
  (Alexander Kanarsky via Shai Erera)
16. LUCENE-2809: Fixed IndexWriter.numDocs to take into account applied but not yet flushed deletes.
  (Mike McCandless)
17. LUCENE-2879: MultiPhraseQuery previously calculated its phrase IDF by summing internally, it now calls Similarity.idfExplain(Collection, IndexSearcher).
  (Robert Muir)
18. LUCENE-2693: RAM used by IndexWriter was slightly incorrectly computed.
  (Jason Rutherglen via Shai Erera)
19. LUCENE-1846: DateTools now uses the US locale everywhere, so DateTools.round() is safe also in strange locales.
  (Uwe Schindler)
20. LUCENE-2891: IndexWriterConfig did not accept -1 in setReaderTermIndexDivisor, which can be used to prevent loading the terms index into memory.
  (Shai Erera)
21. LUCENE-2937: Encoding a float into a byte (e.g. encoding field norms during indexing) had an underflow detection bug that caused floatToByte(f)==0 where f was greater than 0, but slightly less than byteToFloat(1). This meant that certain very small field norms (index_boost * length_norm) could have been rounded down to 0 instead of being rounded up to the smallest positive number.
  (yonik)
22. LUCENE-2936: PhraseQuery score explanations were not correctly identifying matches vs non-matches.
  (hossman)
23. LUCENE-2975: A hotspot bug corrupts IndexInput#readVInt()/readVLong() if the underlying readByte() is inlined (which happens e.g. in MMapDirectory). The loop was unwinded which makes the hotspot bug disappear.
  (Uwe Schindler, Robert Muir, Mike McCandless)
New features (31)
1. LUCENE-2128: Parallelized fetching document frequencies during weight creation.
  (Israel Tsadok, Simon Willnauer via Uwe Schindler)
2. LUCENE-2069: Added Unicode 4 support to CharArraySet. Due to the switch to Java 5, supplementary characters are now lowercased correctly if the set is created as case insensitive. CharArraySet now requires a Version argument to preserve backwards compatibility. If Version < 3.1 is passed to the constructor, CharArraySet yields the old behavior.
  (Simon Willnauer)
3. LUCENE-2069: Added Unicode 4 support to LowerCaseFilter. Due to the switch to Java 5, supplementary characters are now lowercased correctly. LowerCaseFilter now requires a Version argument to preserve backwards compatibility. If Version < 3.1 is passed to the constructor, LowerCaseFilter yields the old behavior.
  (Simon Willnauer, Robert Muir)
4. LUCENE-2034: Added ReusableAnalyzerBase, an abstract subclass of Analyzer that makes it easier to reuse TokenStreams correctly. This issue also added StopwordAnalyzerBase, which improves consistency of all Analyzers that use stopwords, and implement many analyzers in contrib with it.
  (Simon Willnauer via Robert Muir)
5. LUCENE-2198, LUCENE-2901: Support protected words in stemming TokenFilters using a new KeywordAttribute.
  (Simon Willnauer, Drew Farris via Uwe Schindler)
6. LUCENE-2183, LUCENE-2240, LUCENE-2241: Added Unicode 4 support to CharTokenizer and its subclasses. CharTokenizer now has new int-API which is conditionally preferred to the old char-API depending on the provided Version. Version < 3.1 will use the char-API.
  (Simon Willnauer via Uwe Schindler)
7. LUCENE-2247: Added a CharArrayMap<V> for performance improvements in some stemmers and synonym filters.
  (Uwe Schindler)
8. LUCENE-2320: Added SetOnce which wraps an object and allows it to be set exactly once.
  (Shai Erera via Mike McCandless)
9. LUCENE-2314: Added AttributeSource.copyTo(AttributeSource) that allows to use cloneAttributes() and this method as a replacement for captureState()/restoreState(), if the state itself needs to be inspected/modified.
  (Uwe Schindler)
10. LUCENE-2293: Expose control over max number of threads that IndexWriter will allow to run concurrently while indexing documents (previously this was hardwired to 5), using IndexWriterConfig.setMaxThreadStates.
  (Mike McCandless)
11. LUCENE-2297: Enable turning on reader pooling inside IndexWriter even when getReader (near-real-timer reader) is not in use, through IndexWriterConfig.enable/disableReaderPooling.
  (Mike McCandless)
12. LUCENE-2331: Add NoMergePolicy which never returns any merges to execute. In addition, add NoMergeScheduler which never executes any merges. These two are convenient classes in case you want to disable segment merges by IndexWriter without tweaking a particular MergePolicy parameters, such as mergeFactor. MergeScheduler's methods are now public.
  (Shai Erera via Mike McCandless)
13. LUCENE-2339: Deprecate static method Directory.copy in favor of Directory.copyTo, and use nio's FileChannel.transferTo when copying files between FSDirectory instances.
  (Earwin Burrfoot via Mike McCandless).
14. LUCENE-2074: Make StandardTokenizer fit for Unicode 4.0, if the matchVersion parameter is Version.LUCENE_31.
  (Uwe Schindler)
15. LUCENE-2385: Moved NoDeletionPolicy from benchmark to core. NoDeletionPolicy can be used to prevent commits from ever getting deleted from the index.
  (Shai Erera)
16. LUCENE-1585: IndexWriter now accepts a PayloadProcessorProvider which can return a DirPayloadProcessor for a given Directory, which returns a PayloadProcessor for a given Term. The PayloadProcessor will be used to process the payloads of the segments as they are merged (e.g. if one wants to rewrite payloads of external indexes as they are added, or of local ones).
  (Shai Erera, Michael Busch, Mike McCandless)
17. LUCENE-2440: Add support for custom ExecutorService in ParallelMultiSearcher
  (Edward Drapkin via Mike McCandless)
18. LUCENE-2295: Added a LimitTokenCountAnalyzer / LimitTokenCountFilter to wrap any other Analyzer and provide the same functionality as MaxFieldLength provided on IndexWriter. This patch also fixes a bug in the offset calculation in CharTokenizer.
  (Uwe Schindler, Shai Erera)
19. LUCENE-2526: Don't throw NPE from MultiPhraseQuery.toString when it's empty.
  (Ross Woolf via Mike McCandless)
20. LUCENE-2559: Added SegmentReader.reopen methods
  (John Wang via Mike McCandless)
21. LUCENE-2590: Added Scorer.visitSubScorers, and Scorer.freq. Along with a custom Collector these experimental methods make it possible to gather the hit-count per sub-clause and per document while a search is running.
  (Simon Willnauer, Mike McCandless)
22. LUCENE-2636: Added MultiCollector which allows running the search with several Collectors.
  (Shai Erera)
23. LUCENE-2754, LUCENE-2757: Added a wrapper around MultiTermQueries to add span support: SpanMultiTermQueryWrapper<Q extends MultiTermQuery>. Using this wrapper its easy to add fuzzy/wildcard to e.g. a SpanNearQuery.
  (Robert Muir, Uwe Schindler)
24. LUCENE-2838: ConstantScoreQuery now directly supports wrapping a Query instance for stripping off scores. The use of a QueryWrapperFilter is no longer needed and discouraged for that use case. Directly wrapping Query improves performance, as out-of-order collection is now supported.
  (Uwe Schindler)
25. LUCENE-2864: Add getMaxTermFrequency (maximum within-document TF) to FieldInvertState so that it can be used in Similarity.computeNorm.
  (Robert Muir)
26. LUCENE-2720: Segments now record the code version which created them.
  (Shai Erera, Mike McCandless, Uwe Schindler)
27. LUCENE-2474: Added expert ReaderFinishedListener API to IndexReader, to allow apps that maintain external per-segment caches to evict entries when a segment is finished.
  (Shay Banon, Yonik Seeley, Mike McCandless)
28. LUCENE-2911: The new StandardTokenizer, UAX29URLEmailTokenizer, and the ICUTokenizer in contrib now all tag types with a consistent set of token types (defined in StandardTokenizer). Tokens in the major CJK types are explicitly marked to allow for custom downstream handling: <IDEOGRAPHIC>, <HANGUL>, <KATAKANA>, and <HIRAGANA>.
  (Robert Muir, Steven Rowe)
29. LUCENE-2913: Add missing getters to Numeric* classes.
  (Uwe Schindler)
30. LUCENE-1810: Added FieldSelectorResult.LATENT to not cache lazy loaded fields
  (Tim Smith, Grant Ingersoll)
31. LUCENE-2692: Added several new SpanQuery classes for positional checking (match is in a range, payload is a specific value)
  (Grant Ingersoll)
Optimizations (23)
1. LUCENE-2494: Use CompletionService in ParallelMultiSearcher instead of simple polling for results.
  (Edward Drapkin, Simon Willnauer)
2. LUCENE-2075: Terms dict cache is now shared across threads instead of being stored separately in thread local storage. Also fixed terms dict so that the cache is used when seeking the thread local term enum, which will be important for MultiTermQuery impls that do lots of seeking
  (Mike McCandless, Uwe Schindler, Robert Muir, Yonik Seeley)
3. LUCENE-2136: If the multi reader (DirectoryReader or MultiReader) only has a single sub-reader, delegate all enum requests to it. This avoid the overhead of using a PQ unnecessarily.
  (Mike McCandless)
4. LUCENE-2137: Switch to AtomicInteger for some ref counting
  (Earwin Burrfoot via Mike McCandless)
5. LUCENE-2123, LUCENE-2261: Move FuzzyQuery rewrite to separate RewriteMode into MultiTermQuery. The number of fuzzy expansions can be specified with the maxExpansions parameter to FuzzyQuery.
  (Uwe Schindler, Robert Muir, Mike McCandless)
6. LUCENE-2164: ConcurrentMergeScheduler has more control over merge threads. First, it gives smaller merges higher thread priority than larges ones. Second, a new set/getMaxMergeCount setting will pause the larger merges to allow smaller ones to finish. The defaults for these settings are now dynamic, depending the number CPU cores as reported by Runtime.getRuntime().availableProcessors()
  (Mike McCandless)
7. LUCENE-2169: Improved CharArraySet.copy(), if source set is also a CharArraySet.
  (Simon Willnauer via Uwe Schindler)
8. LUCENE-2084: Change IndexableBinaryStringTools to work on byte[] and char[] directly, instead of Byte/CharBuffers, and modify CollationKeyFilter to take advantage of this for faster performance.
  (Steven Rowe, Uwe Schindler, Robert Muir)
9. LUCENE-2188: Add a utility class for tracking deprecated overridden methods in non-final subclasses.
  (Uwe Schindler, Robert Muir)
10. LUCENE-2195: Speedup CharArraySet if set is empty.
  (Simon Willnauer via Robert Muir)
11. LUCENE-2285: Code cleanup.
  (Shai Erera via Uwe Schindler)
12. LUCENE-2303: Remove code duplication in Token class by subclassing TermAttributeImpl, move DEFAULT_TYPE constant to TypeInterface, improve null-handling for TypeAttribute.
  (Uwe Schindler)
13. LUCENE-2329: Switch TermsHash* from using a PostingList object per unique term to parallel arrays, indexed by termID. This reduces garbage collection overhead significantly, which results in great indexing performance wins when the available JVM heap space is low. This will become even more important when the DocumentsWriter RAM buffer is searchable in the future, because then it will make sense to make the RAM buffers as large as possible.
  (Mike McCandless, Michael Busch)
14. LUCENE-2380: The terms field cache methods (getTerms, getTermsIndex), which replace the older String equivalents (getStrings, getStringIndex), consume quite a bit less RAM in most cases.
  (Mike McCandless)
15. LUCENE-2410: ~20% speedup on exact (slop=0) PhraseQuery matching.
  (Mike McCandless)
16. LUCENE-2531: Fix issue when sorting by a String field that was causing too many fallbacks to compare-by-value (instead of by-ord).
  (Mike McCandless)
17. LUCENE-2574: IndexInput exposes copyBytes(IndexOutput, long) to allow for efficient copying by sub-classes. Optimized copy is implemented for RAM and FS streams.
  (Shai Erera)
18. LUCENE-2719: Improved TermsHashPerField's sorting to use a better quick sort algorithm that dereferences the pivot element not on every compare call. Also replaced lots of sorting code in Lucene by the improved SorterTemplate class.
  (Uwe Schindler, Robert Muir, Mike McCandless)
19. LUCENE-2760: Optimize SpanFirstQuery and SpanPositionRangeQuery.
  (Robert Muir)
20. LUCENE-2770: Make SegmentMerger always work on atomic subreaders, even when IndexWriter.addIndexes(IndexReader...) is used with DirectoryReaders or other MultiReaders. This saves lots of memory during merge of norms.
  (Uwe Schindler, Mike McCandless)
21. LUCENE-2824: Optimize BufferedIndexInput to do less bounds checks.
  (Robert Muir)
22. LUCENE-2010: Segments with 100% deleted documents are now removed on IndexReader or IndexWriter commit.
  (Uwe Schindler, Mike McCandless)
23. LUCENE-1472: Removed synchronization from static DateTools methods by using a ThreadLocal. Also converted DateTools.Resolution to a Java 5 enum (this should not break backwards).
  (Uwe Schindler)
Build (8)
1. LUCENE-2124: Moved the JDK-based collation support from contrib/collation into core, and moved the ICU-based collation support into contrib/icu.
  (Robert Muir)
2. LUCENE-2326: Removed SVN checkouts for backwards tests. The backwards branch is now included in the svn repository using "svn copy" after release.
  (Uwe Schindler)
3. LUCENE-2074: Regenerating StandardTokenizerImpl files now needs JFlex 1.5 (currently only available on SVN).
  (Uwe Schindler)
4. LUCENE-1709: Tests are now parallelized by default (except for benchmark). You can force them to run sequentially by passing -Drunsequential=1 on the command line. The number of threads that are spawned per CPU defaults to '1'. If you wish to change that, you can run the tests with -DthreadsPerProcessor=[num].
  (Robert Muir, Shai Erera, Peter Kofler)
5. LUCENE-2516: Backwards tests are now compiled against released lucene-core.jar from tarball of previous version. Backwards tests are now packaged together with src distribution.
  (Uwe Schindler)
6. LUCENE-2611: Added Ant target to install IntelliJ IDEA configuration: "ant idea". See http://wiki.apache.org/lucene-java/HowtoConfigureIntelliJ
  (Steven Rowe)
7. LUCENE-2657: Switch from using Maven POM templates to full POMs when generating Maven artifacts
  (Steven Rowe)
8. LUCENE-2609: Added jar-test-framework Ant target which packages Lucene's tests' framework classes.
  (Drew Farris, Grant Ingersoll, Shai Erera, Steven Rowe)
Test Cases (10)
1. LUCENE-2037 Allow Junit4 tests in our environment
  (Erick Erickson via Mike McCandless)
2. LUCENE-1844: Speed up the unit tests
  (Mark Miller, Erick Erickson, Mike McCandless)
3. LUCENE-2065: Use Java 5 generics throughout our unit tests.
  (Kay Kay via Mike McCandless)
4. LUCENE-2155: Fix time and zone dependent localization test failures in queryparser tests.
  (Uwe Schindler, Chris Male, Robert Muir)
5. LUCENE-2170: Fix thread starvation problems.
  (Uwe Schindler)
6. LUCENE-2248, LUCENE-2251, LUCENE-2285: Refactor tests to not use Version.LUCENE_CURRENT, but instead use a global static value from LuceneTestCase(J4), that contains the release version.
  (Uwe Schindler, Simon Willnauer, Shai Erera)
7. LUCENE-2313, LUCENE-2322: Add VERBOSE to LuceneTestCase(J4) to control verbosity of tests. If VERBOSE==false (default) tests should not print anything other than errors to System.(out|err). The setting can be changed with -Dtests.verbose=true on test invocation.
  (Shai Erera, Paul Elschot, Uwe Schindler)
8. LUCENE-2318: Remove inconsistent system property code for retrieving temp and data directories inside test cases. It is now centralized in LuceneTestCase(J4). Also changed lots of tests to use getClass().getResourceAsStream() to retrieve test data. Tests needing access to "real" files from the test folder itself, can use LuceneTestCase(J4).getDataFile().
  (Uwe Schindler)
9. LUCENE-2398, LUCENE-2611: Improve tests to work better from IDEs such as Eclipse and IntelliJ.
  (Paolo Castagna, Steven Rowe via Robert Muir)
10. LUCENE-2804: add newFSDirectory to LuceneTestCase to create a FSDirectory at random.
  (Shai Erera, Robert Muir)
Documentation (3)
1. LUCENE-2579: Fix oal.search's package.html description of abstract methods.
  (Santiago M. Mola via Mike McCandless)
2. LUCENE-2625: Add a note to IndexReader.termDocs() with additional verbiage that the TermEnum must be seeked since it is unpositioned.
  (Adriano Crestani via Robert Muir)
3. LUCENE-2894: Use google-code-prettify for syntax highlighting in javadoc.
  (Shinichiro Abe, Koji Sekiguchi)

Release 2.9.4 / 3.0.3 [2010-12-03]

Changes in runtime behavior (3)
1. LUCENE-2689: NativeFSLockFactory no longer attempts to acquire a test lock just before the real lock is acquired.
  (Surinder Pal Singh Bindra via Mike McCandless)
2. LUCENE-2762: Fixed bug in IndexWriter causing it to hold open file handles against deleted files when compound-file was enabled (the default) and readers are pooled. As a result of this the peak worst-case free disk space required during optimize is now 3X the index size, when compound file is enabled (else 2X).
  (Mike McCandless)
3. LUCENE-2773: LogMergePolicy accepts a double noCFSRatio (default = 0.1), which means any time a merged segment is greater than 10% of the index size, it will be left in non-compound format even if compound format is on. This change was made to reduce peak transient disk usage during optimize which increased due to LUCENE-2762.
  (Mike McCandless)
Bug fixes (24)
1. LUCENE-2142 (correct fix): FieldCacheImpl.getStringIndex no longer throws an exception when term count exceeds doc count.
  (Mike McCandless, Uwe Schindler)
2. LUCENE-2513: when opening writable IndexReader on a not-current commit, do not overwrite "future" commits.
  (Mike McCandless)
3. LUCENE-2536: IndexWriter.rollback was failing to properly rollback buffered deletions against segments that were flushed
  (Mark Harwood via Mike McCandless)
4. LUCENE-2541: Fixed NumericRangeQuery that returned incorrect results with endpoints near Long.MIN_VALUE and Long.MAX_VALUE: NumericUtils.splitRange() overflowed, if
  - the range contained a LOWER bound that was greater than (Long.MAX_VALUE - (1L << precisionStep))
  - the range contained an UPPER bound that was less than (Long.MIN_VALUE + (1L << precisionStep))
  With standard precision steps around 4, this had no effect on most queries, only those that met the above conditions. Queries with large precision steps failed more easy. Queries with precision step >=64 were not affected. Also 32 bit data types int and float were not affected.
  (Yonik Seeley, Uwe Schindler)
5. LUCENE-2593: Fixed certain rare cases where a disk full could lead to a corrupted index
  (Robert Muir, Mike McCandless)
6. LUCENE-2620: Fixed a bug in WildcardQuery where too many asterisks would result in unbearably slow performance.
  (Nick Barkas via Robert Muir)
7. LUCENE-2627: Fixed bug in MMapDirectory chunking when a file is an exact multiple of the chunk size.
  (Robert Muir)
8. LUCENE-2634: isCurrent on an NRT reader was failing to return false if the writer had just committed
  (Nikolay Zamosenchuk via Mike McCandless)
9. LUCENE-2650: Added extra safety to MMapIndexInput clones to prevent accessing an unmapped buffer if the input is closed
  (Mike McCandless, Uwe Schindler, Robert Muir)
10. LUCENE-2384: Reset zzBuffer in StandardTokenizerImpl when lexer is reset.
  (Ruben Laguna via Uwe Schindler, sub-issue of LUCENE-2074)
11. LUCENE-2658: Exceptions while processing term vectors enabled for multiple fields could lead to invalid ArrayIndexOutOfBoundsExceptions.
  (Robert Muir, Mike McCandless)
12. LUCENE-2235: Implement missing PerFieldAnalyzerWrapper.getOffsetGap().
  (Javier Godoy via Uwe Schindler)
13. LUCENE-2328: Fixed memory leak in how IndexWriter/Reader tracked already sync'd files.
  (Earwin Burrfoot via Mike McCandless)
14. LUCENE-2549: Fix TimeLimitingCollector#TimeExceededException to record the absolute docid.
  (Uwe Schindler)
15. LUCENE-2533: fix FileSwitchDirectory.listAll to not return dups when primary & secondary dirs share the same underlying directory.
  (Michael McCandless)
16. LUCENE-2365: IndexWriter.newestSegment (used normally for testing) is fixed to return null if there are no segments.
  (Karthick Sankarachary via Mike McCandless)
17. LUCENE-2730: Fix two rare deadlock cases in IndexWriter
  (Mike McCandless)
18. LUCENE-2744: CheckIndex was stating total number of fields, not the number that have norms enabled, on the "test: field norms..." output.
  (Mark Kristensson via Mike McCandless)
19. LUCENE-2759: Fixed two near-real-time cases where doc store files may be opened for read even though they are still open for write.
  (Mike McCandless)
20. LUCENE-2618: Fix rare thread safety issue whereby IndexWriter.optimize could sometimes return even though the index wasn't fully optimized
  (Mike McCandless)
21. LUCENE-2767: Fix thread safety issue in addIndexes(IndexReader[]) that could potentially result in index corruption.
  (Mike McCandless)
22. LUCENE-2762: Fixed bug in IndexWriter causing it to hold open file handles against deleted files when compound-file was enabled (the default) and readers are pooled. As a result of this the peak worst-case free disk space required during optimize is now 3X the index size, when compound file is enabled (else 2X).
  (Mike McCandless)
23. LUCENE-2216: OpenBitSet.hashCode returned different hash codes for sets that only differed by trailing zeros.
  (Dawid Weiss, yonik)
24. LUCENE-2782: Fix rare potential thread hazard with IndexWriter.commit
  (Mike McCandless)
API Changes (1)
1. LUCENE-2773: LogMergePolicy accepts a double noCFSRatio (default = 0.1), which means any time a merged segment is greater than 10% of the index size, it will be left in non-compound format even if compound format is on. This change was made to reduce peak transient disk usage during optimize which increased due to LUCENE-2762.
  (Mike McCandless)
Optimizations (2)
1. LUCENE-2556: Improve memory usage after cloning TermAttribute.
  (Adriano Crestani via Uwe Schindler)
2. LUCENE-2098: Improve the performance of BaseCharFilter, especially for large documents.
  (Robin Wojciki, Koji Sekiguchi, Robert Muir)
New features (1)
1. LUCENE-2675 (2.9.4 only): Add support for Lucene 3.0 stored field files also in 2.9. The file format did not change, only the version number was upgraded to mark segments that have no compression. FieldsWriter still only writes 2.9 segments as they could contain compressed fields. This cross-version index format compatibility is provided here solely because Lucene 2.9 and 3.0 have the same bugfix level, features, and the same index format with this slight compression difference. In general, Lucene does not support reading newer indexes with older library versions.
  (Uwe Schindler)
Documentation (1)
1. LUCENE-2239: Documented limitations in NIOFSDirectory and MMapDirectory due to Java NIO behavior when a Thread is interrupted while blocking on IO.
  (Simon Willnauer, Robert Muir)

Release 2.9.3 / 3.0.2 [2010-06-18]

Changes in backwards compatibility policy (1)
1. LUCENE-2135: Added FieldCache.purge(IndexReader) method to the interface. Anyone implementing FieldCache externally will need to fix their code to implement this, on upgrading.
  (Mike McCandless)
Changes in runtime behavior (2)
1. LUCENE-2421: NativeFSLockFactory does not throw LockReleaseFailedException if it cannot delete the lock file, since obtaining the lock does not fail if the file is there.
  (Shai Erera)
2. LUCENE-2060 (2.9.3 only): Changed ConcurrentMergeScheduler's default for maxNumThreads from 3 to 1, because in practice we get the most gains from running a single merge in the backround. More than one concurrent merge causes alot of thrashing (though it's possible on SSD storage that there would be net gains).
  (Jason Rutherglen, Mike McCandless)
Bug fixes (21)
1. LUCENE-2046 (2.9.3 only): IndexReader should not see the index as changed, after IndexWriter.prepareCommit has been called but before IndexWriter.commit is called.
  (Peter Keegan via Mike McCandless)
2. LUCENE-2119: Don't throw NegativeArraySizeException if you pass Integer.MAX_VALUE as nDocs to IndexSearcher search methods.
  (Paul Taylor via Mike McCandless)
3. LUCENE-2142: FieldCacheImpl.getStringIndex no longer throws an exception when term count exceeds doc count.
  (Mike McCandless)
4. LUCENE-2104: NativeFSLock.release() would silently fail if the lock is held by another thread/process.
  (Shai Erera via Uwe Schindler)
5. LUCENE-2283: Use shared memory pool for term vector and stored fields buffers. This memory will be reclaimed if needed according to the configured RAM Buffer Size for the IndexWriter. This also fixes potentially excessive memory usage when many threads are indexing a mix of small and large documents.
  (Tim Smith via Mike McCandless)
6. LUCENE-2300: If IndexWriter is pooling reader (because NRT reader has been obtained), and addIndexes* is run, do not pool the readers from the external directory. This is harmless (NRT reader is correct), but a waste of resources.
  (Mike McCandless)
7. LUCENE-2422: Don't reuse byte[] in IndexInput/Output -- it gains little performance, and ties up possibly large amounts of memory for apps that index large docs.
  (Ross Woolf via Mike McCandless)
8. LUCENE-2387: Don't hang onto Fieldables from the last doc indexed, in IndexWriter, nor the Reader in Tokenizer after close is called.
  (Ruben Laguna, Uwe Schindler, Mike McCandless)
9. LUCENE-2417: IndexCommit did not implement hashCode() and equals() consistently. Now they both take Directory and version into consideration. In addition, all of IndexComnmit methods which threw UnsupportedOperationException are now abstract.
  (Shai Erera)
10. LUCENE-2467: Fixed memory leaks in IndexWriter when large documents are indexed.
  (Mike McCandless)
11. LUCENE-2473: Clicking on the "More Results" link in the luceneweb.war demo resulted in ArrayIndexOutOfBoundsException.
  (Sami Siren via Robert Muir)
12. LUCENE-2476: If any exception is hit init'ing IW, release the write lock (previously we only released on IOException).
  (Tamas Cservenak via Mike McCandless)
13. LUCENE-2478: Fix CachingWrapperFilter to not throw NPE when Filter.getDocIdSet() returns null.
  (Uwe Schindler, Daniel Noll)
14. LUCENE-2468: Allow specifying how new deletions should be handled in CachingWrapperFilter and CachingSpanFilter. By default, new deletions are ignored in CachingWrapperFilter, since typically this filter is AND'd with a query that correctly takes new deletions into account. This should be a performance gain (higher cache hit rate) in apps that reopen readers, or use near-real-time reader (IndexWriter.getReader()), but may introduce invalid search results (allowing deleted docs to be returned) for certain cases, so a new expert ctor was added to CachingWrapperFilter to enforce deletions at a performance cost. CachingSpanFilter by default recaches if there are new deletions
  (Shay Banon via Mike McCandless)
15. LUCENE-2299: If you open an NRT reader while addIndexes* is running, it may miss some segments
  (Earwin Burrfoot via Mike McCandless)
16. LUCENE-2397: Don't throw NPE from SnapshotDeletionPolicy.snapshot if there are no commits yet
  (Shai Erera)
17. LUCENE-2424: Fix FieldDoc.toString to actually return its fields
  (Stephen Green via Mike McCandless)
18. LUCENE-2311: Always pass a "fully loaded" (terms index & doc stores) SegmentsReader to IndexWriter's mergedSegmentWarmer (if set), so that warming is free to do whatever it needs to.
  (Earwin Burrfoot via Mike McCandless)
19. LUCENE-3029: Fix corner case when MultiPhraseQuery is used with zero position-increment tokens that would sometimes assign different scores to identical docs.
  (Mike McCandless)
20. LUCENE-2486: Fixed intermittent FileNotFoundException on doc store files when a mergedSegmentWarmer is set on IndexWriter.
  (Mike McCandless)
21. LUCENE-2130: Fix performance issue when FuzzyQuery runs on a multi-segment index
  (Michael McCandless)
API Changes (2)
1. LUCENE-2281: added doBeforeFlush to IndexWriter to allow extensions to perform operations before flush starts. Also exposed doAfterFlush as protected instead of package-private.
  (Shai Erera via Mike McCandless)
2. LUCENE-2356: Add IndexWriter.set/getReaderTermsIndexDivisor, to set what IndexWriter passes for termsIndexDivisor to the readers it opens internally when applying deletions or creating a near-real-time reader.
  (Earwin Burrfoot via Mike McCandless)
Optimizations (4)
1. LUCENE-2494 (3.0.2 only): Use CompletionService in ParallelMultiSearcher instead of simple polling for results.
  (Edward Drapkin, Simon Willnauer)
2. LUCENE-2135: On IndexReader.close, forcefully evict any entries from the FieldCache rather than waiting for the WeakHashMap to release the reference
  (Mike McCandless)
3. LUCENE-2161: Improve concurrency of IndexReader, especially in the context of near real-time readers.
  (Mike McCandless)
4. LUCENE-2360: Small speedup to recycling of reused per-doc RAM in IndexWriter
  (Robert Muir, Mike McCandless)
Build (1)
1. LUCENE-2488 (2.9.3 only): Support build with JDK 1.4 and exclude Java 1.5 contrib modules on request (pass '-Dforce.jdk14.build=true') when compiling/testing/packaging. This marks the benchmark contrib also as Java 1.5, as it depends on fast-vector-highlighter.
  (Uwe Schindler)

Release 2.9.2 / 3.0.1 [2010-02-26]

Changes in backwards compatibility policy (1)
1. LUCENE-2123 (3.0.1 only): Removed the protected inner class ScoreTerm from FuzzyQuery. The change was needed because the comparator of this class had to be changed in an incompatible way. The class was never intended to be public.
  (Uwe Schindler, Mike McCandless)
Bug fixes (10)
1. LUCENE-2092: BooleanQuery was ignoring disableCoord in its hashCode and equals methods, cause bad things to happen when caching BooleanQueries.
  (Chris Hostetter, Mike McCandless)
2. LUCENE-2095: Fixes: when two threads call IndexWriter.commit() at the same time, it's possible for commit to return control back to one of the threads before all changes are actually committed.
  (Sanne Grinovero via Mike McCandless)
3. LUCENE-2132 (3.0.1 only): Fix the demo result.jsp to use QueryParser with a Version argument.
  (Brian Li via Robert Muir)
4. LUCENE-2166: Don't incorrectly keep warning about the same immense term, when IndexWriter.infoStream is on.
  (Mike McCandless)
5. LUCENE-2158: At high indexing rates, NRT reader could temporarily lose deletions.
  (Mike McCandless)
6. LUCENE-2182: DEFAULT_ATTRIBUTE_FACTORY was failing to load implementation class when interface was loaded by a different class loader.
  (Uwe Schindler, reported on java-user by Ahmed El-dawy)
7. LUCENE-2257: Increase max number of unique terms in one segment to termIndexInterval (default 128) * ~2.1 billion = ~274 billion.
  (Tom Burton-West via Mike McCandless)
8. LUCENE-2260: Fixed AttributeSource to not hold a strong reference to the Attribute/AttributeImpl classes which prevents unloading of custom attributes loaded by other classloaders (e.g. in Solr plugins).
  (Uwe Schindler)
9. LUCENE-1941: Fix Min/MaxPayloadFunction returns 0 when only one payload is present.
  (Erik Hatcher, Mike McCandless via Uwe Schindler)
10. LUCENE-2270: Queries consisting of all zero-boost clauses (for example, text:foo^0) sorted incorrectly and produced invalid docids.
  (yonik)
API Changes (4)
1. LUCENE-1609 (3.0.1 only): Restore IndexReader.getTermInfosIndexDivisor (it was accidentally removed in 3.0.0)
  (Mike McCandless)
2. LUCENE-1972 (3.0.1 only): Restore SortField.getComparatorSource (it was accidentally removed in 3.0.0)
  (John Wang via Uwe Schindler)
3. LUCENE-2190: Added a new class CustomScoreProvider to function package that can be subclassed to provide custom scoring to CustomScoreQuery. The methods in CustomScoreQuery that did this before were deprecated and replaced by a method getCustomScoreProvider(IndexReader) that returns a custom score implementation using the above class. The change is necessary with per-segment searching, as CustomScoreQuery is a stateless class (like all other Queries) and does not know about the currently searched segment. This API works similar to Filter's getDocIdSet(IndexReader).
  (Paul chez Jamespot via Mike McCandless, Uwe Schindler)
4. LUCENE-2080: Deprecate Version.LUCENE_CURRENT, as using this constant will cause backwards compatibility problems when upgrading Lucene. See the Version javadocs for additional information.
  (Robert Muir)
Optimizations (3)
1. LUCENE-2086: When resolving deleted terms, do so in term sort order for better performance
  (Bogdan Ghidireac via Mike McCandless)
2. LUCENE-2123 (partly, 3.0.1 only): Fixes a slowdown / memory issue added by LUCENE-504.
  (Uwe Schindler, Robert Muir, Mike McCandless)
3. LUCENE-2258: Remove unneeded synchronization in FuzzyTermEnum.
  (Uwe Schindler, Robert Muir)
Test Cases (3)
1. LUCENE-2114: Change TestFilteredSearch to test on multi-segment index as well.
  (Simon Willnauer via Mike McCandless)
2. LUCENE-2211: Improves BaseTokenStreamTestCase to use a fake attribute that checks if clearAttributes() was called correctly.
  (Uwe Schindler, Robert Muir)
3. LUCENE-2207, LUCENE-2219: Improve BaseTokenStreamTestCase to check if end() is implemented correctly.
  (Koji Sekiguchi, Robert Muir)
Documentation (1)
1. LUCENE-2114: Improve javadocs of Filter to call out that the provided reader is per-segment
  (Simon Willnauer via Mike McCandless)

Release 3.0.0 [2009-11-25]

Changes in backwards compatibility policy (7)
1. LUCENE-1979: Change return type of SnapshotDeletionPolicy#snapshot() from IndexCommitPoint to IndexCommit. Code that uses this method needs to be recompiled against Lucene 3.0 in order to work. The previously deprecated IndexCommitPoint is also removed.
  (Michael Busch)
2. o.a.l.Lock.isLocked() is now allowed to throw an IOException.
  (Mike McCandless)
3. LUCENE-2030: CachingWrapperFilter and CachingSpanFilter now hide the internal cache implementation for thread safety, before it was declared protected.
  (Peter Lenahan, Uwe Schindler, Simon Willnauer)
4. LUCENE-2053: If you call Thread.interrupt() on a thread inside Lucene, Lucene will do its best to interrupt the thread. However, instead of throwing InterruptedException (which is a checked exception), you'll get an oal.util.ThreadInterruptedException (an unchecked exception, subclassing RuntimeException). The interrupt status on the thread is cleared when this exception is thrown.
  (Mike McCandless)
5. LUCENE-2052: Some methods in Lucene core were changed to accept Java 5 varargs. This is not a backwards compatibility problem as long as you not try to override such a method. We left common overridden methods unchanged and added varargs to constructors, static, or final methods (MultiSearcher,...).
  (Uwe Schindler)
6. LUCENE-1558: IndexReader.open(Directory) now opens a readOnly=true reader, and new IndexSearcher(Directory) does the same. Note that this is a change in the default from 2.9, when these methods were previously deprecated.
  (Mike McCandless)
7. LUCENE-1753: Make not yet final TokenStreams final to enforce decorator pattern.
  (Uwe Schindler)
Changes in runtime behavior (3)
1. LUCENE-1677: Remove the system property to set SegmentReader class implementation.
  (Uwe Schindler)
2. LUCENE-1960: As a consequence of the removal of Field.Store.COMPRESS, support for this type of fields was removed. Lucene 3.0 is still able to read indexes with compressed fields, but as soon as merges occur or the index is optimized, all compressed fields are decompressed and converted to Field.Store.YES. Because of this, indexes with compressed fields can suddenly get larger. Also the first merge with decompression cannot be done in raw mode, it is therefore slower. This change has no effect for code that uses such old indexes, they behave as before (fields are automatically decompressed during read). Indexes converted to Lucene 3.0 format cannot be read anymore with previous versions. It is recommended to optimize your indexes after upgrading to convert to the new format and decompress all fields. If you want compressed fields, you can use CompressionTools, that creates compressed byte[] to be added as binary stored field. This cannot be done automatically, as you also have to decompress such fields when reading. You have to reindex to do that.
  (Michael Busch, Uwe Schindler)
3. LUCENE-2060: Changed ConcurrentMergeScheduler's default for maxNumThreads from 3 to 1, because in practice we get the most gains from running a single merge in the background. More than one concurrent merge causes a lot of thrashing (though it's possible on SSD storage that there would be net gains).
  (Jason Rutherglen, Mike McCandless)
API Changes (6)
1. LUCENE-1257, LUCENE-1984, LUCENE-1985, LUCENE-2057, LUCENE-1833, LUCENE-2012, LUCENE-1998: Port to Java 1.5:
  - Add generics to public and internal APIs (see below).
  - Replace new Integer(int), new Double(double),... by static valueOf() calls.
  - Replace for-loops with Iterator by foreach loops.
  - Replace StringBuffer with StringBuilder.
  - Replace o.a.l.util.Parameter by Java 5 enums (see below).
  - Add @Override annotations.
  (Uwe Schindler, Robert Muir, Karl Wettin, Paul Elschot, Kay Kay, Shai Erera, DM Smith)
2. Generify Lucene API:
  - TokenStream/AttributeSource: Now addAttribute()/getAttribute() return an instance of the requested attribute interface and no cast needed anymore (LUCENE-1855).
  - NumericRangeQuery, NumericRangeFilter, and FieldCacheRangeFilter now have Integer, Long, Float, Double as type param (LUCENE-1857).
  - Document.getFields() returns List<Fieldable>.
  - Query.extractTerms
    (Set<Term>)
  - CharArraySet and stop word sets in core/contrib
  - PriorityQueue (LUCENE-1935)
  - TopDocCollector
  - DisjunctionMaxQuery (LUCENE-1984)
  - MultiTermQueryWrapperFilter
  - CloseableThreadLocal
  - MapOfSets
  - o.a.l.util.cache package
  - lot's of internal APIs of IndexWriter
    (Uwe Schindler, Michael Busch, Kay Kay, Robert Muir, Adriano Crestani)
3. LUCENE-1944, LUCENE-1856, LUCENE-1957, LUCENE-1960, LUCENE-1961, LUCENE-1968, LUCENE-1970, LUCENE-1946, LUCENE-1971, LUCENE-1975, LUCENE-1972, LUCENE-1978, LUCENE-944, LUCENE-1979, LUCENE-1973, LUCENE-2011: Remove deprecated methods/constructors/classes:
  - Remove all String/File directory paths in IndexReader / IndexSearcher / IndexWriter.
  - Remove FSDirectory.getDirectory()
  - Make FSDirectory abstract.
  - Remove Field.Store.COMPRESS (see above).
  - Remove Filter.bits(IndexReader) method and make Filter.getDocIdSet(IndexReader) abstract.
  - Remove old DocIdSetIterator methods and make the new ones abstract.
  - Remove some methods in PriorityQueue.
  - Remove old TokenStream API and backwards compatibility layer.
  - Remove RangeQuery, RangeFilter and ConstantScoreRangeQuery.
  - Remove SpanQuery.getTerms().
  - Remove ExtendedFieldCache, custom and auto caches, SortField.AUTO.
  - Remove old-style custom sort.
  - Remove legacy search setting in SortField.
  - Remove Hits and all references from core and contrib.
  - Remove HitCollector and its TopDocs support implementations.
  - Remove term field and accessors in MultiTermQuery (and fix Highlighter).
  - Remove deprecated methods in BooleanQuery.
  - Remove deprecated methods in Similarity.
  - Remove BoostingTermQuery.
  - Remove MultiValueSource.
  - Remove Scorer.explain
    (int).
  ...and some other minor ones
  (Uwe Schindler, Michael Busch, Mark Miller)
4. LUCENE-1925: Make IndexSearcher's subReaders and docStarts members protected; add expert ctor to directly specify reader, subReaders and docStarts.
  (John Wang, Tim Smith via Mike McCandless)
5. LUCENE-1945: All public classes that have a close() method now also implement java.io.Closeable (IndexReader, IndexWriter, Directory,...).
  (Uwe Schindler)
6. LUCENE-1998: Change all Parameter instances to Java 5 enums. This is no backwards-break, only a change of the super class. Parameter was deprecated and will be removed in a later version.
  (DM Smith, Uwe Schindler)
Bug fixes (5)
1. LUCENE-1951: When the text provided to WildcardQuery has no wildcard characters (ie matches a single term), don't lose the boost and rewrite method settings. Also, rewrite to PrefixQuery if the wildcard is form "foo*", for slightly faster performance.
  (Robert Muir via Mike McCandless)
2. LUCENE-2013: SpanRegexQuery does not work with QueryScorer.
  (Benjamin Keil via Mark Miller)
3. LUCENE-2088: addAttribute() should only accept interfaces that extend Attribute.
  (Shai Erera, Uwe Schindler)
4. LUCENE-2045: Fix silly FileNotFoundException hit if you enable infoStream on IndexWriter and then add an empty document and commit
  (Shai Erera via Mike McCandless)
5. LUCENE-2046: IndexReader should not see the index as changed, after IndexWriter.prepareCommit has been called but before IndexWriter.commit is called.
  (Peter Keegan via Mike McCandless)
New features (3)
1. LUCENE-1933: Provide a convenience AttributeFactory that creates a Token instance for all basic attributes.
  (Uwe Schindler)
2. LUCENE-2041: Parallelize the rest of ParallelMultiSearcher. Lots of code refactoring and Java 5 concurrent support in MultiSearcher.
  (Joey Surls, Simon Willnauer via Uwe Schindler)
3. LUCENE-2051: Add CharArraySet.copy() as a simple method to copy any Set<?> to a CharArraySet that is optimized, if Set<?> is already an CharArraySet.
  (Simon Willnauer)
Optimizations (3)
1. LUCENE-1183: Optimize Levenshtein Distance computation in FuzzyQuery.
  (Cédrik Lime via Mike McCandless)
2. LUCENE-2006: Optimization of FieldDocSortedHitQueue to always use Comparable<?> interface.
  (Uwe Schindler, Mark Miller)
3. LUCENE-2087: Remove recursion in NumericRangeTermEnum.
  (Uwe Schindler)
Build (2)
1. LUCENE-486: Remove test->demo dependencies.
  (Michael Busch)
2. LUCENE-2024: Raise build requirements to Java 1.5 and ANT 1.7.0
  (Uwe Schindler, Mike McCandless)

Release 2.9.1 [2009-11-06]

Changes in backwards compatibility policy (1)
1. LUCENE-2002: Add required Version matchVersion argument when constructing QueryParser or MultiFieldQueryParser and, default (as of 2.9) enablePositionIncrements to true to match StandardAnalyzer's 2.9 default
  (Uwe Schindler, Mike McCandless)
Bug fixes (8)
1. LUCENE-1974: Fixed nasty bug in BooleanQuery (when it used BooleanScorer for scoring), whereby some matching documents fail to be collected.
  (Fulin Tang via Mike McCandless)
2. LUCENE-1124: Make sure FuzzyQuery always matches the precise term.
  (stefatwork@gmail.com via Mike McCandless)
3. LUCENE-1976: Fix IndexReader.isCurrent() to return the right thing when the reader is a near real-time reader.
  (Jake Mannix via Mike McCandless)
4. LUCENE-1986: Fix NPE when scoring PayloadNearQuery
  (Peter Keegan, Mark Miller via Mike McCandless)
5. LUCENE-1992: Fix thread hazard if a merge is committing just as an exception occurs during sync
  (Uwe Schindler, Mike McCandless)
6. LUCENE-1995: Note in javadocs that IndexWriter.setRAMBufferSizeMB cannot exceed 2048 MB, and throw IllegalArgumentException if it does.
  (Aaron McKee, Yonik Seeley, Mike McCandless)
7. LUCENE-2004: Fix Constants.LUCENE_MAIN_VERSION to not be inlined by client code.
  (Uwe Schindler)
8. LUCENE-2016: Replace illegal U+FFFF character with the replacement char (U+FFFD) during indexing, to prevent silent index corruption.
  (Peter Keegan, Mike McCandless)
API Changes (5)
1. Un-deprecate search(Weight weight, Filter filter, int n) from Searchable interface (deprecated by accident).
  (Uwe Schindler)
2. Un-deprecate o.a.l.util.Version constants.
  (Mike McCandless)
3. LUCENE-1987: Un-deprecate some ctors of Token, as they will not be removed in 3.0 and are still useful. Also add some missing o.a.l.util.Version constants for enabling invalid acronym settings in StandardAnalyzer to be compatible with the coming Lucene 3.0.
  (Uwe Schindler)
4. LUCENE-1973: Un-deprecate IndexSearcher.setDefaultFieldSortScoring, to allow controlling per-IndexSearcher whether scores are computed when sorting by field.
  (Uwe Schindler, Mike McCandless)
5. LUCENE-2043: Make IndexReader.commit(Map<String,String>) public.
  (Mike McCandless)
Documentation (3)
1. LUCENE-1955: Fix Hits deprecation notice to point users in right direction.
  (Mike McCandless, Mark Miller)
2. Fix javadoc about score tracking done by search methods in Searcher and IndexSearcher.
  (Mike McCandless)
3. LUCENE-2008: Javadoc improvements for TokenStream/Tokenizer/Token
  (Luke Nezda via Mike McCandless)

Release 2.9.0 [2009-09-25]

Changes in backwards compatibility policy (8)
1. LUCENE-1575: Searchable.search(Weight, Filter, int, Sort) no longer computes a document score for each hit by default. If document score tracking is still needed, you can call IndexSearcher.setDefaultFieldSortScoring(true, true) to enable both per-hit and maxScore tracking; however, this is deprecated and will be removed in 3.0.
  Alternatively, use Searchable.search(Weight, Filter, Collector) and pass in a TopFieldCollector instance, using the following code sample:
```
   TopFieldCollector tfc = TopFieldCollector.create(sort, numHits, fillFields,
                                                    true /* trackDocScores */,
                                                    true /* trackMaxScore */,
                                                    false /* docsInOrder */);
   searcher.search(query, tfc);
   TopDocs results = tfc.topDocs();
```
  Note that your Sort object cannot use SortField.AUTO when you directly instantiate TopFieldCollector.
  Also, the method search(Weight, Filter, Collector) was added to the Searchable interface and the Searcher abstract class to replace the deprecated HitCollector versions. If you either implement Searchable or extend Searcher, you should change your code to implement this method. If you already extend IndexSearcher, no further changes are needed to use Collector.
  Finally, the values Float.NaN and Float.NEGATIVE_INFINITY are not valid scores. Lucene uses these values internally in certain places, so if you have hits with such scores, it will cause problems.
  (Shai Erera via Mike McCandless)
2. LUCENE-1687: All methods and parsers from the interface ExtendedFieldCache have been moved into FieldCache. ExtendedFieldCache is now deprecated and contains only a few declarations for binary backwards compatibility. ExtendedFieldCache will be removed in version 3.0. Users of FieldCache and ExtendedFieldCache will be able to plug in Lucene 2.9 without recompilation. The auto cache (FieldCache.getAuto) is now deprecated. Due to the merge of ExtendedFieldCache and FieldCache, FieldCache can now additionally return long[] and double[] arrays in addition to int[] and float[] and StringIndex.
  The interface changes are only notable for users implementing the interfaces, which was unlikely done, because there is no possibility to change Lucene's FieldCache implementation.
  (Grant Ingersoll, Uwe Schindler)
3. LUCENE-1630, LUCENE-1771: Weight, previously an interface, is now an abstract class. Some of the method signatures have changed, but it should be fairly easy to see what adjustments must be made to existing code to sync up with the new API. You can find more detail in the API Changes section.
  Going forward Searchable will be kept for convenience only and may be changed between minor releases without any deprecation process. It is not recommended that you implement it, but rather extend Searcher.
  (Shai Erera, Chris Hostetter, Martin Ruckli, Mark Miller via Mike McCandless)
4. LUCENE-1422, LUCENE-1693: The new Attribute based TokenStream API (see below) has some backwards breaks in rare cases. We did our best to make the transition as easy as possible and you are not likely to run into any problems. If your tokenizers still implement next(Token) or next(), the calls are automatically wrapped. The indexer and query parser use the new API (eg use incrementToken() calls). All core TokenStreams are implemented using the new API. You can mix old and new API style TokenFilters/TokenStream. Problems only occur when you have done the following: You have overridden next(Token) or next() in one of the non-abstract core TokenStreams/-Filters. These classes should normally be final, but some of them are not. In this case, next(Token)/next() would never be called. To fail early with a hard compile/runtime error, the next(Token)/next() methods in these TokenStreams/-Filters were made final in this release.
  (Michael Busch, Uwe Schindler)
5. LUCENE-1763: MergePolicy now requires an IndexWriter instance to be passed upon instantiation. As a result, IndexWriter was removed as a method argument from all MergePolicy methods.
  (Shai Erera via Mike McCandless)
6. LUCENE-1748: LUCENE-1001 introduced PayloadSpans, but this was a back compat break and caused custom SpanQuery implementations to fail at runtime in a variety of ways. This issue attempts to remedy things by causing a compile time break on custom SpanQuery implementations and removing the PayloadSpans class, with its functionality now moved to Spans. To help in alleviating future back compat pain, Spans has been changed from an interface to an abstract class.
  (Hugh Cayless, Mark Miller)
7. LUCENE-1808: Query.createWeight has been changed from protected to public. This will be a back compat break if you have overridden this method - but you are likely already affected by the LUCENE-1693 (make Weight abstract rather than an interface) back compat break if you have overridden Query.creatWeight, so we have taken the opportunity to make this change.
  (Tim Smith, Shai Erera via Mark Miller)
8. LUCENE-1708 - IndexReader.document() no longer checks if the document is deleted. You can call IndexReader.isDeleted(n) prior to calling document(n).
  (Shai Erera via Mike McCandless)
Changes in runtime behavior (14)
1. LUCENE-1424: QueryParser now by default uses constant score auto rewriting when it generates a WildcardQuery and PrefixQuery (it already does so for TermRangeQuery, as well). Call setMultiTermRewriteMethod(MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE) to revert to slower BooleanQuery rewriting method.
  (Mark Miller via Mike McCandless)
2. LUCENE-1575: As of 2.9, the core collectors as well as IndexSearcher's search methods that return top N results, no longer filter documents with scores <= 0.0. If you rely on this functionality you can use PositiveScoresOnlyCollector like this:
```
   TopDocsCollector tdc = new TopScoreDocCollector(10);
   Collector c = new PositiveScoresOnlyCollector(tdc);
   searcher.search(query, c);
   TopDocs hits = tdc.topDocs();
   ...
```
3. LUCENE-1604: IndexReader.norms(String field) is now allowed to return null if the field has no norms, as long as you've previously called IndexReader.setDisableFakeNorms(true). This setting now defaults to false (to preserve the fake norms back compatible behavior) but in 3.0 will be hardwired to true.
  (Shon Vella via Mike McCandless).
4. LUCENE-1624: If you open IndexWriter with create=true and autoCommit=false on an existing index, IndexWriter no longer writes an empty commit when it's created.
  (Paul Taylor via Mike McCandless)
5. LUCENE-1593: When you call Sort() or Sort.setSort(String field, boolean reverse), the resulting SortField array no longer ends with SortField.FIELD_DOC (it was unnecessary as Lucene breaks ties internally by docID).
  (Shai Erera via Michael McCandless)
6. LUCENE-1542: When the first token(s) have 0 position increment, IndexWriter used to incorrectly record the position as -1, if no payload is present, or Integer.MAX_VALUE if a payload is present. This causes positional queries to fail to match. The bug is now fixed, but if your app relies on the buggy behavior then you must call IndexWriter.setAllowMinus1Position(). That API is deprecated so you must fix your application, and rebuild your index, to not rely on this behavior by the 3.0 release of Lucene.
  (Jonathan Mamou, Mark Miller via Mike McCandless)
7. LUCENE-1715: Finalizers have been removed from the 4 core classes that still had them, since they will cause GC to take longer, thus tying up memory for longer, and at best they mask buggy app code. DirectoryReader (returned from IndexReader.open) & IndexWriter previously released the write lock during finalize. SimpleFSDirectory.FSIndexInput closed the descriptor in its finalizer, and NativeFSLock released the lock. It's possible applications will be affected by this, but only if the application is failing to close reader/writers.
  (Brian Groose via Mike McCandless)
8. LUCENE-1717: Fixed IndexWriter to account for RAM usage of buffered deletions.
  (Mike McCandless)
9. LUCENE-1727: Ensure that fields are stored & retrieved in the exact order in which they were added to the document. This was true in all Lucene releases before 2.3, but was broken in 2.3 and 2.4, and is now fixed in 2.9.
  (Mike McCandless)
10. LUCENE-1678: The addition of Analyzer.reusableTokenStream accidentally broke back compatibility of external analyzers that subclassed core analyzers that implemented tokenStream but not reusableTokenStream. This is now fixed, such that if reusableTokenStream is invoked on such a subclass, that method will forcefully fallback to tokenStream.
  (Mike McCandless)
11. LUCENE-1801: Token.clear() and Token.clearNoTermBuffer() now also clear startOffset, endOffset and type. This is not likely to affect any Tokenizer chains, as Tokenizers normally always set these three values. This change was made to be conform to the new AttributeImpl.clear() and AttributeSource.clearAttributes() to work identical for Token as one for all AttributeImpl and the 6 separate AttributeImpls.
  (Uwe Schindler, Michael Busch)
12. LUCENE-1483: When searching over multiple segments, a new Scorer is now created for each segment. Searching has been telescoped out a level and IndexSearcher now operates much like MultiSearcher does. The Weight is created only once for the top level Searcher, but each Scorer is passed a per-segment IndexReader. This will result in doc ids in the Scorer being internal to the per-segment IndexReader. It has always been outside of the API to count on a given IndexReader to contain every doc id in the index - and if you have been ignoring MultiSearcher in your custom code and counting on this fact, you will find your code no longer works correctly. If a custom Scorer implementation uses any caches/filters that rely on being based on the top level IndexReader, it will need to be updated to correctly use contextless caches/filters eg you can't count on the IndexReader to contain any given doc id or all of the doc ids.
  (Mark Miller, Mike McCandless)
13. LUCENE-1846: DateTools now uses the US locale to format the numbers in its date/time strings instead of the default locale. For most locales there will be no change in the index format, as DateFormatSymbols is using ASCII digits. The usage of the US locale is important to guarantee correct ordering of generated terms.
  (Uwe Schindler)
14. LUCENE-1860: MultiTermQuery now defaults to CONSTANT_SCORE_AUTO_REWRITE_DEFAULT rewrite method (previously it was SCORING_BOOLEAN_QUERY_REWRITE). This means that PrefixQuery and WildcardQuery will now produce constant score for all matching docs, equal to the boost of the query.
  (Mike McCandless)
API Changes (38)
1. LUCENE-1419: Add expert API to set custom indexing chain. This API is package-protected for now, so we don't have to officially support it. Yet, it will give us the possibility to try out different consumers in the chain.
  (Michael Busch)
2. LUCENE-1427: DocIdSet.iterator() is now allowed to throw IOException.
  (Paul Elschot, Mike McCandless)
3. LUCENE-1422, LUCENE-1693: New TokenStream API that uses a new class called AttributeSource instead of the Token class, which is now a utility class that holds common Token attributes. All attributes that the Token class had have been moved into separate classes: TermAttribute, OffsetAttribute, PositionIncrementAttribute, PayloadAttribute, TypeAttribute and FlagsAttribute. The new API is much more flexible; it allows to combine the Attributes arbitrarily and also to define custom Attributes. The new API has the same performance as the old next(Token) approach. For conformance with this new API Tee-/SinkTokenizer was deprecated and replaced by a new TeeSinkTokenFilter.
  (Michael Busch, Uwe Schindler; additional contributions and bug fixes by Daniel Shane, Doron Cohen)
4. LUCENE-1467: Add nextDoc() and next(int) methods to OpenBitSetIterator. These methods can be used to avoid additional calls to doc().
  (Michael Busch)
5. LUCENE-1468: Deprecate Directory.list(), which sometimes (in FSDirectory) filters out files that don't look like index files, in favor of new Directory.listAll(), which does no filtering. Also, listAll() will never return null; instead, it throws an IOException (or subclass). Specifically, FSDirectory.listAll() will throw the newly added NoSuchDirectoryException if the directory does not exist.
  (Marcel Reutegger, Mike McCandless)
6. LUCENE-1546: Add IndexReader.flush(Map commitUserData), allowing you to record an opaque commitUserData (maps String -> String) into the commit written by IndexReader. This matches IndexWriter's commit methods.
  (Jason Rutherglen via Mike McCandless)
7. LUCENE-652: Added org.apache.lucene.document.CompressionTools, to enable compressing & decompressing binary content, external to Lucene's indexing. Deprecated Field.Store.COMPRESS.
8. LUCENE-1561: Renamed Field.omitTf to Field.omitTermFreqAndPositions
  (Otis Gospodnetic via Mike McCandless)
9. LUCENE-1500: Added new InvalidTokenOffsetsException to Highlighter methods to denote issues when offsets in TokenStream tokens exceed the length of the provided text.
  (Mark Harwood)
10. LUCENE-1575, LUCENE-1483: HitCollector is now deprecated in favor of a new Collector abstract class. For easy migration, people can use HitCollectorWrapper which translates (wraps) HitCollector into Collector. Note that this class is also deprecated and will be removed when HitCollector is removed. Also TimeLimitedCollector is deprecated in favor of the new TimeLimitingCollector which extends Collector.
  (Shai Erera, Mark Miller, Mike McCandless)
11. LUCENE-1592: The method TermsEnum.skipTo() was deprecated, because it is used nowhere in core/contrib and there is only a very ineffective default implementation available. If you want to position a TermEnum to another Term, create a new one using IndexReader.terms(Term).
  (Uwe Schindler)
12. LUCENE-1621: MultiTermQuery.getTerm() has been deprecated as it does not make sense for all subclasses of MultiTermQuery. Check individual subclasses to see if they support getTerm().
  (Mark Miller)
13. LUCENE-1636: Make TokenFilter.input final so it's set only once.
  (Wouter Heijke, Uwe Schindler via Mike McCandless).
14. LUCENE-1658, LUCENE-1451: Renamed FSDirectory to SimpleFSDirectory (but left an FSDirectory base class). Added an FSDirectory.open static method to pick a good default FSDirectory implementation given the OS. FSDirectories should now be instantiated using FSDirectory.open or with public constructors rather than FSDirectory.getDirectory(), which has been deprecated.
  (Michael McCandless, Uwe Schindler, yonik)
15. LUCENE-1665: Deprecate SortField.AUTO, to be removed in 3.0. Instead, when sorting by field, the application should explicitly state the type of the field.
  (Mike McCandless)
16. LUCENE-1660: StopFilter, StandardAnalyzer, StopAnalyzer now require up front specification of enablePositionIncrement
  (Mike McCandless)
17. LUCENE-1614: DocIdSetIterator's next() and skipTo() were deprecated in favor of the new nextDoc() and advance(). The new methods return the doc Id they landed on, saving an extra call to doc() in most cases. For easy migration of the code, you can change the calls to next() to nextDoc() != DocIdSetIterator.NO_MORE_DOCS and similarly for skipTo(). However it is advised that you take advantage of the returned doc ID and not call doc() following those two. Also, doc() was deprecated in favor of docID(). docID() should return -1 or NO_MORE_DOCS if nextDoc/advance were not called yet, or NO_MORE_DOCS if the iterator has exhausted. Otherwise it should return the current doc ID.
  (Shai Erera via Mike McCandless)
18. LUCENE-1672: All ctors/opens and other methods using String/File to specify the directory in IndexReader, IndexWriter, and IndexSearcher were deprecated. You should instantiate the Directory manually before and pass it to these classes (LUCENE-1451, LUCENE-1658).
  (Uwe Schindler)
19. LUCENE-1407: Move RemoteSearchable, RemoteCachingWrapperFilter out of Lucene's core into new contrib/remote package. Searchable no longer extends java.rmi.Remote
  (Simon Willnauer via Mike McCandless)
20. LUCENE-1677: The global property org.apache.lucene.SegmentReader.class, and ReadOnlySegmentReader.class are now deprecated, to be removed in 3.0. src/gcj/* has been removed.
  (Earwin Burrfoot via Mike McCandless)
21. LUCENE-1673: Deprecated NumberTools in favour of the new NumericRangeQuery and its new indexing format for numeric or date values.
  (Uwe Schindler)
22. LUCENE-1630, LUCENE-1771: Weight is now an abstract class, and adds a scorer(IndexReader, boolean /* scoreDocsInOrder */, boolean /* topScorer */) method instead of scorer(IndexReader). IndexSearcher uses this method to obtain a scorer matching the capabilities of the Collector wrt orderedness of docIDs. Some Scorers (like BooleanScorer) are much more efficient if out-of-order documents scoring is allowed by a Collector. Collector must now implement acceptsDocsOutOfOrder. If you write a Collector which does not care about doc ID orderness, it is recommended that you return true. Weight has a scoresDocsOutOfOrder method, which by default returns false. If you create a Weight which will score documents out of order if requested, you should override that method to return true. BooleanQuery's setAllowDocsOutOfOrder and getAllowDocsOutOfOrder have been deprecated as they are not needed anymore. BooleanQuery will now score docs out of order when used with a Collector that can accept docs out of order. Finally, Weight#explain now takes a sub-reader and sub-docID, rather than a top level reader and docID.
  (Shai Erera, Chris Hostetter, Martin Ruckli, Mark Miller via Mike McCandless)
23. LUCENE-1466, LUCENE-1906: Added CharFilter and MappingCharFilter, which allows chaining & mapping of characters before tokenizers run. CharStream (subclass of Reader) is the base class for custom java.io.Reader's, that support offset correction. Tokenizers got an additional method correctOffset() that is passed down to the underlying CharStream if input is a subclass of CharStream/-Filter.
  (Koji Sekiguchi via Mike McCandless, Uwe Schindler)
24. LUCENE-1703: Add IndexWriter.waitForMerges.
  (Tim Smith via Mike McCandless)
25. LUCENE-1625: CheckIndex's programmatic API now returns separate classes detailing the status of each component in the index, and includes more detailed status than previously.
  (Tim Smith via Mike McCandless)
26. LUCENE-1713: Deprecated RangeQuery and RangeFilter and renamed to TermRangeQuery and TermRangeFilter. TermRangeQuery is in constant score auto rewrite mode by default. The new classes also have new ctors taking field and term ranges as Strings (see also LUCENE-1424).
  (Uwe Schindler)
27. LUCENE-1609: The termInfosIndexDivisor must now be specified up-front when opening the IndexReader. Attempts to call IndexReader.setTermInfosIndexDivisor will hit an UnsupportedOperationException. This was done to enable removal of all synchronization in TermInfosReader, which previously could cause threads to pile up in certain cases.
  (Dan Rosher via Mike McCandless)
28. LUCENE-1688: Deprecate static final String stop word array in and StopAnalzyer and replace it with an immutable implementation of CharArraySet.
  (Simon Willnauer via Mark Miller)
29. LUCENE-1742: SegmentInfos, SegmentInfo and SegmentReader have been made public as expert, experimental APIs. These APIs may suddenly change from release to release
  (Jason Rutherglen via Mike McCandless).
30. LUCENE-1754: QueryWeight.scorer() can return null if no documents are going to be matched by the query. Similarly, Filter.getDocIdSet() can return null if no documents are going to be accepted by the Filter. Note that these 'can' return null, however they don't have to and can return a Scorer/DocIdSet which does not match / reject all documents. This is already the behavior of some QueryWeight/Filter implementations, and is documented here just for emphasis.
  (Shai Erera via Mike McCandless)
31. LUCENE-1705: Added IndexWriter.deleteAllDocuments.
  (Tim Smith via Mike McCandless)
32. LUCENE-1460: Changed TokenStreams/TokenFilters in contrib to use the new TokenStream API.
  (Robert Muir, Michael Busch)
33. LUCENE-1748: LUCENE-1001 introduced PayloadSpans, but this was a back compat break and caused custom SpanQuery implementations to fail at runtime in a variety of ways. This issue attempts to remedy things by causing a compile time break on custom SpanQuery implementations and removing the PayloadSpans class, with its functionality now moved to Spans. To help in alleviating future back compat pain, Spans has been changed from an interface to an abstract class.
  (Hugh Cayless, Mark Miller)
34. LUCENE-1808: Query.createWeight has been changed from protected to public.
  (Tim Smith, Shai Erera via Mark Miller)
35. LUCENE-1826: Add constructors that take AttributeSource and AttributeFactory to all Tokenizer implementations.
  (Michael Busch)
36. LUCENE-1847: Similarity#idf for both a Term and Term Collection have been deprecated. New versions that return an IDFExplanation have been added.
  (Yasoja Seneviratne, Mike McCandless, Mark Miller)
37. LUCENE-1877: Made NativeFSLockFactory the default for the new FSDirectory API (open(), FSDirectory subclass ctors). All FSDirectory system properties were deprecated and all lock implementations use no lock prefix if the locks are stored inside the index directory. Because the deprecated String/File ctors of IndexWriter and IndexReader (LUCENE-1672) and FSDirectory.getDirectory() still use the old SimpleFSLockFactory and the new API NativeFSLockFactory, we strongly recommend not to mix deprecated and new API.
  (Uwe Schindler, Mike McCandless)
38. LUCENE-1911: Added a new method isCacheable() to DocIdSet. This method should return true, if the underlying implementation does not use disk I/O and is fast enough to be directly cached by CachingWrapperFilter. OpenBitSet, SortedVIntList, and DocIdBitSet are such candidates. The default implementation of the abstract DocIdSet class returns false. In this case, CachingWrapperFilter copies the DocIdSetIterator into an OpenBitSet for caching.
  (Uwe Schindler, Thomas Becker)
Bug fixes (26)
1. LUCENE-1415: MultiPhraseQuery has incorrect hashCode() and equals() implementation - Leads to Solr Cache misses.
  (Todd Feak, Mark Miller via yonik)
2. LUCENE-1327: Fix TermSpans#skipTo() to behave as specified in javadocs of Terms#skipTo().
  (Michael Busch)
3. LUCENE-1573: Do not ignore InterruptedException (caused by Thread.interrupt()) nor enter deadlock/spin loop. Now, an interrupt will cause a RuntimeException to be thrown. In 3.0 we will change public APIs to throw InterruptedException.
  (Jeremy Volkman via Mike McCandless)
4. LUCENE-1590: Fixed stored-only Field instances do not change the value of omitNorms, omitTermFreqAndPositions in FieldInfo; when you retrieve such fields they will now have omitNorms=true and omitTermFreqAndPositions=false (though these values are unused).
  (Uwe Schindler via Mike McCandless)
5. LUCENE-1587: RangeQuery#equals() could consider a RangeQuery without a collator equal to one with a collator.
  (Mark Platvoet via Mark Miller)
6. LUCENE-1600: Don't call String.intern unnecessarily in some cases when loading documents from the index.
  (P Eger via Mike McCandless)
7. LUCENE-1611: Fix case where OutOfMemoryException in IndexWriter could cause "infinite merging" to happen.
  (Christiaan Fluit via Mike McCandless)
8. LUCENE-1623: Properly handle back-compatibility of 2.3.x indexes that contain field names with non-ascii characters.
  (Mike Streeton via Mike McCandless)
9. LUCENE-1593: MultiSearcher and ParallelMultiSearcher did not break ties (in sort) by doc Id in a consistent manner (i.e., if Sort.FIELD_DOC was used vs. when it wasn't).
  (Shai Erera via Michael McCandless)
10. LUCENE-1647: Fix case where IndexReader.undeleteAll would cause the segment's deletion count to be incorrect.
  (Mike McCandless)
11. LUCENE-1542: When the first token(s) have 0 position increment, IndexWriter used to incorrectly record the position as -1, if no payload is present, or Integer.MAX_VALUE if a payload is present. This causes positional queries to fail to match. The bug is now fixed, but if your app relies on the buggy behavior then you must call IndexWriter.setAllowMinus1Position(). That API is deprecated so you must fix your application, and rebuild your index, to not rely on this behavior by the 3.0 release of Lucene.
  (Jonathan Mamou, Mark Miller via Mike McCandless)
12. LUCENE-1658: Fixed MMapDirectory to correctly throw IOExceptions on EOF, removed numeric overflow possibilities and added support for a hack to unmap the buffers on closing IndexInput.
  (Uwe Schindler)
13. LUCENE-1681: Fix infinite loop caused by a call to DocValues methods getMinValue, getMaxValue, getAverageValue.
  (Simon Willnauer via Mark Miller)
14. LUCENE-1599: Add clone support for SpanQuerys. SpanRegexQuery counts on this functionality and does not work correctly without it.
  (Billow Gao, Mark Miller)
15. LUCENE-1718: Fix termInfosIndexDivisor to carry over to reopened readers
  (Mike McCandless)
16. LUCENE-1583: SpanOrQuery skipTo() doesn't always move forwards as Spans documentation indicates it should.
  (Moti Nisenson via Mark Miller)
17. LUCENE-1566: Sun JVM Bug http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6478546 causes invalid OutOfMemoryError when reading too many bytes at once from a file on 32bit JVMs that have a large maximum heap size. This fix adds set/getReadChunkSize to FSDirectory so that large reads are broken into chunks, to work around this JVM bug. On 32bit JVMs the default chunk size is 100 MB; on 64bit JVMs, which don't show the bug, the default is Integer.MAX_VALUE.
  (Simon Willnauer via Mike McCandless)
18. LUCENE-1448: Added TokenStream.end() to perform end-of-stream operations (ie to return the end offset of the tokenization). This is important when multiple fields with the same name are added to a document, to ensure offsets recorded in term vectors for all of the instances are correct.
  (Mike McCandless, Mark Miller, Michael Busch)
19. LUCENE-1805: CloseableThreadLocal did not allow a null Object in get(), although it does allow it in set(Object). Fix get() to not assert the object is not null.
  (Shai Erera via Mike McCandless)
20. LUCENE-1801: Changed all Tokenizers or TokenStreams in core/contrib) that are the source of Tokens to always call AttributeSource.clearAttributes() first.
  (Uwe Schindler)
21. LUCENE-1819: MatchAllDocsQuery.toString(field) should produce output that is parsable by the QueryParser.
  (John Wang, Mark Miller)
22. LUCENE-1836: Fix localization bug in the new query parser and add new LocalizedTestCase as base class for localization junit tests.
  (Robert Muir, Uwe Schindler via Michael Busch)
23. LUCENE-1847: PhraseQuery/TermQuery/SpanQuery use IndexReader specific stats in their Weight#explain methods - these stats should be corpus wide.
  (Yasoja Seneviratne, Mike McCandless, Mark Miller)
24. LUCENE-1885: Fix the bug that NativeFSLock.isLocked() did not work, if the lock was obtained by another NativeFSLock(Factory) instance. Because of this IndexReader.isLocked() and IndexWriter.isLocked() did not work correctly.
  (Uwe Schindler)
25. LUCENE-1899: Fix O(N^2) CPU cost when setting docIDs in order in an OpenBitSet, due to an inefficiency in how the underlying storage is reallocated.
  (Nadav Har'El via Mike McCandless)
26. LUCENE-1918: Fixed cases where a ParallelReader would generate exceptions on being passed to IndexWriter.addIndexes(IndexReader[]). First case was when the ParallelReader was empty. Second case was when the ParallelReader used to contain documents with TermVectors, but all such documents have been deleted.
  (Christian Kohlschütter via Mike McCandless)
New features (36)
1. LUCENE-1411: Added expert API to open an IndexWriter on a prior commit, obtained from IndexReader.listCommits. This makes it possible to rollback changes to an index even after you've closed the IndexWriter that made the changes, assuming you are using an IndexDeletionPolicy that keeps past commits around. This is useful when building transactional support on top of Lucene.
  (Mike McCandless)
2. LUCENE-1382: Add an optional arbitrary Map (String -> String) "commitUserData" to IndexWriter.commit(), which is stored in the segments file and is then retrievable via IndexReader.getCommitUserData instance and static methods.
  (Shalin Shekhar Mangar via Mike McCandless)
3. LUCENE-1420: Similarity now has a computeNorm method that allows custom Similarity classes to override how norm is computed. It's provided a FieldInvertState instance that contains details from inverting the field. The default impl is boost * lengthNorm(numTerms), to be backwards compatible. Also added {set/get}DiscountOverlaps to DefaultSimilarity, to control whether overlapping tokens (tokens with 0 position increment) should be counted in lengthNorm.
  (Andrzej Bialecki via Mike McCandless)
4. LUCENE-1424: Moved constant score query rewrite capability into MultiTermQuery, allowing TermRangeQuery, PrefixQuery and WildcardQuery to switch between constant-score rewriting or BooleanQuery expansion rewriting via a new setRewriteMethod method. Deprecated ConstantScoreRangeQuery
  (Mark Miller via Mike McCandless)
5. LUCENE-1461: Added FieldCacheRangeFilter, a RangeFilter for single-term fields that uses FieldCache to compute the filter. If your documents all have a single term for a given field, and you need to create many RangeFilters with varying lower/upper bounds, then this is likely a much faster way to create the filters than RangeFilter. FieldCacheRangeFilter allows ranges on all data types, FieldCache supports (term ranges, byte, short, int, long, float, double). However, it comes at the expense of added RAM consumption and slower first-time usage due to populating the FieldCache. It also does not support collation
  (Tim Sturge, Matt Ericson via Mike McCandless and Uwe Schindler)
6. LUCENE-1296: add protected method CachingWrapperFilter.docIdSetToCache to allow subclasses to choose which DocIdSet implementation to use
  (Paul Elschot via Mike McCandless)
7. LUCENE-1390: Added ASCIIFoldingFilter, a Filter that converts alphabetic, numeric, and symbolic Unicode characters which are not in the first 127 ASCII characters (the "Basic Latin" Unicode block) into their ASCII equivalents, if one exists. ISOLatin1AccentFilter, which handles a subset of this filter, has been deprecated.
  (Andi Vajda, Steven Rowe via Mark Miller)
8. LUCENE-1478: Added new SortField constructor allowing you to specify a custom FieldCache parser to generate numeric values from terms for a field.
  (Uwe Schindler via Mike McCandless)
9. LUCENE-1528: Add support for Ideographic Space to the queryparser.
  (Luis Alves via Michael Busch)
10. LUCENE-1487: Added FieldCacheTermsFilter, to filter by multiple terms on single-valued fields. The filter loads the FieldCache for the field the first time it's called, and subsequent usage of that field, even with different Terms in the filter, are fast.
  (Tim Sturge, Shalin Shekhar Mangar via Mike McCandless).
11. LUCENE-1314: Add clone(), clone(boolean readOnly) and reopen(boolean readOnly) to IndexReader. Cloning an IndexReader gives you a new reader which you can make changes to (deletions, norms) without affecting the original reader. Now, with clone or reopen you can change the readOnly of the original reader.
  (Jason Rutherglen, Mike McCandless)
12. LUCENE-1506: Added FilteredDocIdSet, an abstract class which you subclass to implement the "match" method to accept or reject each docID. Unlike ChainedFilter (under contrib/misc), FilteredDocIdSet never requires you to materialize the full bitset. Instead, match() is called on demand per docID.
  (John Wang via Mike McCandless)
13. LUCENE-1398: Add ReverseStringFilter to contrib/analyzers, a filter to reverse the characters in each token.
  (Koji Sekiguchi via yonik)
14. LUCENE-1551: Add expert IndexReader.reopen(IndexCommit) to allow efficiently opening a new reader on a specific commit, sharing resources with the original reader.
  (Torin Danil via Mike McCandless)
15. LUCENE-1434: Added org.apache.lucene.util.IndexableBinaryStringTools, to encode byte[] as String values that are valid terms, and maintain sort order of the original byte[] when the bytes are interpreted as unsigned.
  (Steven Rowe via Mike McCandless)
16. LUCENE-1543: Allow MatchAllDocsQuery to optionally use norms from a specific fields to set the score for a document.
  (Karl Wettin via Mike McCandless)
17. LUCENE-1586: Add IndexReader.getUniqueTermCount().
  (Mike McCandless via Derek)
18. LUCENE-1516: Added "near real-time search" to IndexWriter, via a new expert getReader() method. This method returns a reader that searches the full index, including any uncommitted changes in the current IndexWriter session. This should result in a faster turnaround than the normal approach of commiting the changes and then reopening a reader.
  (Jason Rutherglen via Mike McCandless)
19. LUCENE-1603: Added new MultiTermQueryWrapperFilter, to wrap any MultiTermQuery as a Filter. Also made some improvements to MultiTermQuery: return DocIdSet.EMPTY_DOCIDSET if there are no terms in the enum; track the total number of terms it visited during rewrite (getTotalNumberOfTerms). FilteredTermEnum is also more friendly to subclassing.
  (Uwe Schindler via Mike McCandless)
20. LUCENE-1605: Added BitVector.subset().
  (Jeremy Volkman via Mike McCandless)
21. LUCENE-1618: Added FileSwitchDirectory that enables files with specified extensions to be stored in a primary directory and the rest of the files to be stored in the secondary directory. For example, this can be useful for the large doc-store (stored fields, term vectors) files in FSDirectory and the rest of the index files in a RAMDirectory.
  (Jason Rutherglen via Mike McCandless)
22. LUCENE-1494: Added FieldMaskingSpanQuery which can be used to cross-correlate Spans from different fields.
  (Paul Cowan and Chris Hostetter)
23. LUCENE-1634: Add calibrateSizeByDeletes to LogMergePolicy, to take deletions into account when considering merges.
  (Yasuhiro Matsuda via Mike McCandless)
24. LUCENE-1550: Added new n-gram based String distance measure for spell checking. See the Javadocs for NGramDistance.java for a reference paper on why this is helpful
  (Tom Morton via Grant Ingersoll)
25. LUCENE-1470, LUCENE-1582, LUCENE-1602, LUCENE-1673, LUCENE-1701, LUCENE-1712: Added NumericRangeQuery and NumericRangeFilter, a fast alternative to RangeQuery/RangeFilter for numeric searches. They depend on a specific structure of terms in the index that can be created by indexing using the new NumericField or NumericTokenStream classes. NumericField can only be used for indexing and optionally stores the values as string representation in the doc store. Documents returned from IndexReader/IndexSearcher will return only the String value using the standard Fieldable interface. NumericFields can be sorted on and loaded into the FieldCache.
  (Uwe Schindler, Yonik Seeley, Mike McCandless)
26. LUCENE-1405: Added support for Ant resource collections in contrib/ant <index> task.
  (Przemyslaw Sztoch via Erik Hatcher)
27. LUCENE-1699: Allow setting a TokenStream on Field/Fieldable for indexing in conjunction with any other ways to specify stored field values, currently binary or string values.
  (yonik)
28. LUCENE-1701: Made the standard FieldCache.Parsers public and added parsers for fields generated using NumericField/NumericTokenStream. All standard parsers now also implement Serializable and enforce their singleton status.
  (Uwe Schindler, Mike McCandless)
29. LUCENE-1741: User configurable maximum chunk size in MMapDirectory. On 32 bit platforms, the address space can be very fragmented, so one big ByteBuffer for the whole file may not fit into address space.
  (Eks Dev via Uwe Schindler)
30. LUCENE-1644: Enable 4 rewrite modes for queries deriving from MultiTermQuery (WildcardQuery, PrefixQuery, TermRangeQuery, NumericRangeQuery): CONSTANT_SCORE_FILTER_REWRITE first creates a filter and then assigns constant score (boost) to docs; CONSTANT_SCORE_BOOLEAN_QUERY_REWRITE create a BooleanQuery but uses a constant score (boost); SCORING_BOOLEAN_QUERY_REWRITE also creates a BooleanQuery but keeps the BooleanQuery's scores; CONSTANT_SCORE_AUTO_REWRITE tries to pick the most performant constant-score rewrite method.
  (Mike McCandless)
31. LUCENE-1448: Added TokenStream.end(), to perform end-of-stream operations. This is currently used to fix offset problems when multiple fields with the same name are added to a document.
  (Mike McCandless, Mark Miller, Michael Busch)
32. LUCENE-1776: Add an option to not collect payloads for an ordered SpanNearQuery. Payloads were not lazily loaded in this case as the javadocs implied. If you have payloads and want to use an ordered SpanNearQuery that does not need to use the payloads, you can disable loading them with a new constructor switch.
  (Mark Miller)
33. LUCENE-1341: Added PayloadNearQuery to enable SpanNearQuery functionality with payloads
  (Peter Keegan, Grant Ingersoll, Mark Miller)
34. LUCENE-1790: Added PayloadTermQuery to enable scoring of payloads based on the maximum payload seen for a document. Slight refactoring of Similarity and other payload queries
  (Grant Ingersoll, Mark Miller)
35. LUCENE-1749: Addition of FieldCacheSanityChecker utility, and hooks to use it in all existing Lucene Tests. This class can be used by any application to inspect the FieldCache and provide diagnostic information about the possibility of inconsistent FieldCache usage. Namely: FieldCache entries for the same field with different datatypes or parsers; and FieldCache entries for the same field in both a reader, and one of it's (descendant) sub readers.
  (Chris Hostetter, Mark Miller)
36. LUCENE-1789: Added utility class oal.search.function.MultiValueSource to ease the transition to segment based searching for any apps that directly call oal.search.function.* APIs. This class wraps any other ValueSource, but takes care when composite (multi-segment) are passed to not double RAM usage in the FieldCache.
  (Chris Hostetter, Mark Miller, Mike McCandless)
Optimizations (13)
1. LUCENE-1427: Fixed QueryWrapperFilter to not waste time computing scores of the query, since they are just discarded. Also, made it more efficient (single pass) by not creating & populating an intermediate OpenBitSet
  (Paul Elschot, Mike McCandless)
2. LUCENE-1443: Performance improvement for OpenBitSetDISI.inPlaceAnd()
  (Paul Elschot via yonik)
3. LUCENE-1484: Remove synchronization of IndexReader.document() by using CloseableThreadLocal internally.
  (Jason Rutherglen via Mike McCandless).
4. LUCENE-1124: Short circuit FuzzyQuery.rewrite when input token length is small compared to minSimilarity.
  (Timo Nentwig, Mark Miller)
5. LUCENE-1316: MatchAllDocsQuery now avoids the synchronized IndexReader.isDeleted() call per document, by directly accessing the underlying deleteDocs BitVector. This improves performance with non-readOnly readers, especially in a multi-threaded environment.
  (Todd Feak, Yonik Seeley, Jason Rutherglen via Mike McCandless)
6. LUCENE-1483: When searching over multiple segments we now visit each sub-reader one at a time. This speeds up warming, since FieldCache entries (if required) can be shared across reopens for those segments that did not change, and also speeds up searches that sort by relevance or by field values.
  (Mark Miller, Mike McCandless)
7. LUCENE-1575: The new Collector class decouples collect() from score computation. Collector.setScorer is called to establish the current Scorer in-use per segment. Collectors that require the score should then call Scorer.score() per hit inside collect().
  (Shai Erera via Mike McCandless)
8. LUCENE-1596: MultiTermDocs speedup when set with MultiTermDocs.seek(MultiTermEnum)
  (yonik)
9. LUCENE-1653: Avoid creating a Calendar in every call to DateTools#dateToString, DateTools#timeToString and DateTools#round.
  (Shai Erera via Mark Miller)
10. LUCENE-1688: Deprecate static final String stop word array and replace it with an immutable implementation of CharArraySet. Removes conversions between Set and array.
  (Simon Willnauer via Mark Miller)
11. LUCENE-1754: BooleanQuery.queryWeight.scorer() will return null if it won't match any documents (e.g. if there are no required and optional scorers, or not enough optional scorers to satisfy minShouldMatch).
  (Shai Erera via Mike McCandless)
12. LUCENE-1607: To speed up string interning for commonly used strings, the StringHelper.intern() interface was added with a default implementation that uses a lockless cache.
  (Earwin Burrfoot, yonik)
13. LUCENE-1800: QueryParser should use reusable TokenStreams.
  (yonik)
Documentation (9)
1. LUCENE-1908: Scoring documentation imrovements in Similarity javadocs.
  (Mark Miller, Shai Erera, Ted Dunning, Jiri Kuhn, Marvin Humphrey, Doron Cohen)
2. LUCENE-1872: NumericField javadoc improvements
  (Michael McCandless, Uwe Schindler)
3. LUCENE-1875: Make TokenStream.end javadoc less confusing.
  (Uwe Schindler)
4. LUCENE-1862: Rectified duplicate package level javadocs for o.a.l.queryParser and o.a.l.analysis.cn.
  (Chris Hostetter)
5. LUCENE-1886: Improved hyperlinking in key Analysis javadocs
  (Bernd Fondermann via Chris Hostetter)
6. LUCENE-1884: massive javadoc and comment cleanup, primarily dealing with typos.
  (Robert Muir via Chris Hostetter)
7. LUCENE-1898: Switch changes to use bullets rather than numbers and update changes-to-html script to handle the new format.
  (Steven Rowe, Mark Miller)
8. LUCENE-1900: Improve Searchable Javadoc.
  (Nadav Har'El, Doron Cohen, Marvin Humphrey, Mark Miller)
9. LUCENE-1896: Improve Similarity#queryNorm javadocs.
  (Jiri Kuhn, Mark Miller)
Build (5)
1. LUCENE-1440: Add new targets to build.xml that allow downloading and executing the junit testcases from an older release for backwards-compatibility testing.
  (Michael Busch)
2. LUCENE-1446: Add compatibility tag to common-build.xml and run backwards-compatibility tests in the nightly build.
  (Michael Busch)
3. LUCENE-1529: Properly test "drop-in" replacement of jar with backwards-compatibility tests.
  (Mike McCandless, Michael Busch)
4. LUCENE-1851: Change 'javacc' and 'clean-javacc' targets to build and clean contrib/surround files.
  (Luis Alves via Michael Busch)
5. LUCENE-1854: tar task should use longfile="gnu" to avoid false file name length warnings.
  (Mark Miller)
Test Cases (4)
1. LUCENE-1791: Enhancements to the QueryUtils and CheckHits utility classes to wrap IndexReaders and Searchers in MultiReaders or MultiSearcher when possible to help exercise more edge cases.
  (Chris Hostetter, Mark Miller)
2. LUCENE-1852: Fix localization test failures.
  (Robert Muir via Michael Busch)
3. LUCENE-1843: Refactored all tests that use assertAnalyzesTo() & others in core and contrib to use a new BaseTokenStreamTestCase base class. Also rewrote some tests to use this general analysis assert functions instead of own ones (e.g. TestMappingCharFilter). The new base class also tests tokenization with the TokenStream.next() backwards layer enabled (using Token/TokenWrapper as attribute implementation) and disabled (default for Lucene 3.0)
  (Uwe Schindler, Robert Muir)
4. LUCENE-1836: Added a new LocalizedTestCase as base class for localization junit tests.
  (Robert Muir, Uwe Schindler via Michael Busch)

Release 2.4.1 [2009-03-09]

API Changes (1)
1. LUCENE-1186: Add Analyzer.close() to free internal ThreadLocal resources.
  (Christian Kohlschütter via Mike McCandless)
Bug fixes (15)
1. LUCENE-1452: Fixed silent data-loss case whereby binary fields are truncated to 0 bytes during merging if the segments being merged are non-congruent (same field name maps to different field numbers). This bug was introduced with LUCENE-1219.
  (Andrzej Bialecki via Mike McCandless).
2. LUCENE-1429: Don't throw incorrect IllegalStateException from IndexWriter.close() if you've hit an OOM when autoCommit is true.
  (Mike McCandless)
3. LUCENE-1474: If IndexReader.flush() is called twice when there were pending deletions, it could lead to later false AssertionError during IndexReader.open.
  (Mike McCandless)
4. LUCENE-1430: Fix false AlreadyClosedException from IndexReader.open (masking an actual IOException) that takes String or File path.
  (Mike McCandless)
5. LUCENE-1442: Multiple-valued NOT_ANALYZED fields can double-count token offsets.
  (Mike McCandless)
6. LUCENE-1453: Ensure IndexReader.reopen()/clone() does not result in incorrectly closing the shared FSDirectory. This bug would only happen if you use IndexReader.open() with a File or String argument. The returned readers are wrapped by a FilterIndexReader that correctly handles closing of directory after reopen()/clone().
  (Mark Miller, Uwe Schindler, Mike McCandless)
7. LUCENE-1457: Fix possible overflow bugs during binary searches.
  (Mark Miller via Mike McCandless)
8. LUCENE-1459: Fix CachingWrapperFilter to not throw exception if both bits() and getDocIdSet() methods are called.
  (Matt Jones via Mike McCandless)
9. LUCENE-1519: Fix int overflow bug during segment merging.
  (Deepak via Mike McCandless)
10. LUCENE-1521: Fix int overflow bug when flushing segment.
  (Shon Vella via Mike McCandless).
11. LUCENE-1544: Fix deadlock in IndexWriter.addIndexes(IndexReader[]).
  (Mike McCandless via Doug Sale)
12. LUCENE-1547: Fix rare thread safety issue if two threads call IndexWriter commit() at the same time.
  (Mike McCandless)
13. LUCENE-1465: NearSpansOrdered returns payloads from first possible match rather than the correct, shortest match; Payloads could be returned even if the max slop was exceeded; The wrong payload could be returned in certain situations.
  (Jonathan Mamou, Greg Shackles, Mark Miller)
14. LUCENE-1186: Add Analyzer.close() to free internal ThreadLocal resources.
  (Christian Kohlschütter via Mike McCandless)
15. LUCENE-1552: Fix IndexWriter.addIndexes(IndexReader[]) to properly rollback IndexWriter's internal state on hitting an exception.
  (Scott Garland via Mike McCandless)

Release 2.4.0 [2008-10-08]

Changes in backwards compatibility policy (1)
1. LUCENE-1340: In a minor change to Lucene's backward compatibility policy, we are now allowing the Fieldable interface to have changes, within reason, and made on a case-by-case basis. If an application implements it's own Fieldable, please be aware of this. Otherwise, no need to be concerned. This is in effect for all 2.X releases, starting with 2.4. Also note, that in all likelihood, Fieldable will be changed in 3.0.
Changes in runtime behavior (4)
1. LUCENE-1151: Fix StandardAnalyzer to not mis-identify host names (eg lucene.apache.org) as an ACRONYM. To get back to the pre-2.4 backwards compatible, but buggy, behavior, you can either call StandardAnalyzer.setDefaultReplaceInvalidAcronym(false) (static method), or, set system property org.apache.lucene.analysis.standard.StandardAnalyzer.replaceInvalidAcronym to "false" on JVM startup. All StandardAnalyzer instances created after that will then show the pre-2.4 behavior. Alternatively, you can call setReplaceInvalidAcronym(false) to change the behavior per instance of StandardAnalyzer. This backwards compatibility will be removed in 3.0 (hardwiring the value to true).
  (Mike McCandless)
2. LUCENE-1044: IndexWriter with autoCommit=true now commits (such that a reader can see the changes) far less often than it used to. Previously, every flush was also a commit. You can always force a commit by calling IndexWriter.commit(). Furthermore, in 3.0, autoCommit will be hardwired to false (IndexWriter constructors that take an autoCommit argument have been deprecated)
  (Mike McCandless)
3. LUCENE-1335: IndexWriter.addIndexes(Directory[]) and addIndexesNoOptimize no longer allow the same Directory instance to be passed in more than once. Internally, IndexWriter uses Directory and segment name to uniquely identify segments, so adding the same Directory more than once was causing duplicates which led to problems
  (Mike McCandless)
4. LUCENE-1396: Improve PhraseQuery.toString() so that gaps in the positions are indicated with a ? and multiple terms at the same position are joined with a |.
  (Andrzej Bialecki via Mike McCandless)
API Changes (26)
1. LUCENE-1084: Changed all IndexWriter constructors to take an explicit parameter for maximum field size. Deprecated all the pre-existing constructors; these will be removed in release 3.0. NOTE: these new constructors set autoCommit to false.
  (Steven Rowe via Mike McCandless)
2. LUCENE-584: Changed Filter API to return a DocIdSet instead of a java.util.BitSet. This allows using more efficient data structures for Filters and makes them more flexible. This deprecates Filter.bits(), so all filters that implement this outside the Lucene code base will need to be adapted. See also the javadocs of the Filter class.
  (Paul Elschot, Michael Busch)
3. LUCENE-1044: Added IndexWriter.commit() which flushes any buffered adds/deletes and then commits a new segments file so readers will see the changes. Deprecate IndexWriter.flush() in favor of IndexWriter.commit().
  (Mike McCandless)
4. LUCENE-325: Added IndexWriter.expungeDeletes methods, which consult the MergePolicy to find merges necessary to merge away all deletes from the index. This should be a somewhat lower cost operation than optimize.
  (John Wang via Mike McCandless)
5. LUCENE-1233: Return empty array instead of null when no fields match the specified name in these methods in Document: getFieldables, getFields, getValues, getBinaryValues.
  (Stefan Trcek vai Mike McCandless)
6. LUCENE-1234: Make BoostingSpanScorer protected.
  (Andi Vajda via Grant Ingersoll)
7. LUCENE-510: The index now stores strings as true UTF-8 bytes (previously it was Java's modified UTF-8). If any text, either stored fields or a token, has illegal UTF-16 surrogate characters, these characters are now silently replaced with the Unicode replacement character U+FFFD. This is a change to the index file format.
  (Marvin Humphrey via Mike McCandless)
8. LUCENE-852: Let the SpellChecker caller specify IndexWriter mergeFactor and RAM buffer size.
  (Otis Gospodnetic)
9. LUCENE-1290: Deprecate org.apache.lucene.search.Hits, Hit and HitIterator and remove all references to these classes from the core. Also update demos and tutorials.
  (Michael Busch)
10. LUCENE-1288: Add getVersion() and getGeneration() to IndexCommit. getVersion() returns the same value that IndexReader.getVersion() returns when the reader is opened on the same commit.
  (Jason Rutherglen via Mike McCandless)
11. LUCENE-1311: Added IndexReader.listCommits(Directory) static method to list all commits in a Directory, plus IndexReader.open methods that accept an IndexCommit and open the index as of that commit. These methods are only useful if you implement a custom DeletionPolicy that keeps more than the last commit around.
  (Jason Rutherglen via Mike McCandless)
12. LUCENE-1325: Added IndexCommit.isOptimized().
  (Shalin Shekhar Mangar via Mike McCandless)
13. LUCENE-1324: Added TokenFilter.reset().
  (Shai Erera via Mike McCandless)
14. LUCENE-1340: Added Fieldable.omitTf() method to skip indexing term frequency, positions and payloads. This saves index space, and indexing/searching time.
  (Eks Dev via Mike McCandless)
15. LUCENE-1219: Add basic reuse API to Fieldable for binary fields: getBinaryValue/Offset/Length(); currently only lazy fields reuse the provided byte[] result to getBinaryValue.
  (Eks Dev via Mike McCandless)
16. LUCENE-1334: Add new constructor for Term: Term(String fieldName) which defaults term text to "".
  (DM Smith via Mike McCandless)
17. LUCENE-1333: Added Token.reinit(*) APIs to re-initialize (reuse) a Token. Also added term() method to return a String, with a performance penalty clearly documented. Also implemented hashCode() and equals() in Token, and fixed all core and contrib analyzers to use the re-use APIs.
  (DM Smith via Mike McCandless)
18. LUCENE-1329: Add optional readOnly boolean when opening an IndexReader. A readOnly reader is not allowed to make changes (deletions, norms) to the index; in exchanged, the isDeleted method, often a bottleneck when searching with many threads, is not synchronized. The default for readOnly is still false, but in 3.0 the default will become true.
  (Jason Rutherglen via Mike McCandless)
19. LUCENE-1367: Add IndexCommit.isDeleted().
  (Shalin Shekhar Mangar via Mike McCandless)
20. LUCENE-1061: Factored out all "new XXXQuery(...)" in QueryParser.java into protected methods newXXXQuery(...) so that subclasses can create their own subclasses of each Query type.
  (John Wang via Mike McCandless)
21. LUCENE-753: Added new Directory implementation org.apache.lucene.store.NIOFSDirectory, which uses java.nio's FileChannel to do file reads. On most non-Windows platforms, with many threads sharing a single searcher, this may yield sizable improvement to query throughput when compared to FSDirectory, which only allows a single thread to read from an open file at a time.
  (Jason Rutherglen via Mike McCandless)
22. LUCENE-1371: Added convenience method TopDocs Searcher.search(Query query, int n).
  (Mike McCandless)
23. LUCENE-1356: Allow easy extensions of TopDocCollector by turning constructor and fields from package to protected.
  (Shai Erera via Doron Cohen)
24. LUCENE-1375: Added convenience method IndexCommit.getTimestamp, which is equivalent to getDirectory().fileModified(getSegmentsFileName()).
  (Mike McCandless)
25. LUCENE-1366: Rename Field.Index options to be more accurate: TOKENIZED becomes ANALYZED; UN_TOKENIZED becomes NOT_ANALYZED; NO_NORMS becomes NOT_ANALYZED_NO_NORMS and a new ANALYZED_NO_NORMS is added.
  (Mike McCandless)
26. LUCENE-1131: Added numDeletedDocs method to IndexReader
  (Otis Gospodnetic)
Bug fixes (16)
1. LUCENE-1134: Fixed BooleanQuery.rewrite to only optimize a single clause query if minNumShouldMatch<=0.
  (Shai Erera via Michael Busch)
2. LUCENE-1169: Fixed bug in IndexSearcher.search(): searching with a filter might miss some hits because scorer.skipTo() is called without checking if the scorer is already at the right position. scorer.skipTo(scorer.doc()) is not a NOOP, it behaves as scorer.next().
  (Eks Dev, Michael Busch)
3. LUCENE-1182: Added scorePayload to SimilarityDelegator
  (Andi Vajda via Grant Ingersoll)
4. LUCENE-1213: MultiFieldQueryParser was ignoring slop in case of a single field phrase.
  (Trejkaz via Doron Cohen)
5. LUCENE-1228: IndexWriter.commit() was not updating the index version and as result IndexReader.reopen() failed to sense index changes.
  (Doron Cohen)
6. LUCENE-1267: Added numDocs() and maxDoc() to IndexWriter; deprecated docCount().
  (Mike McCandless)
7. LUCENE-1274: Added new prepareCommit() method to IndexWriter, which does phase 1 of a 2-phase commit (commit() does phase 2). This is needed when you want to update an index as part of a transaction involving external resources (eg a database). Also deprecated abort(), renaming it to rollback().
  (Mike McCandless)
8. LUCENE-1003: Stop RussianAnalyzer from removing numbers.
  (TUSUR OpenTeam, Dmitry Lihachev via Otis Gospodnetic)
9. LUCENE-1152: SpellChecker fix around clearIndex and indexDictionary methods, plus removal of IndexReader reference.
  (Naveen Belkale via Otis Gospodnetic)
10. LUCENE-1046: Removed dead code in SpellChecker
  (Daniel Naber via Otis Gospodnetic)
11. LUCENE-1189: Fixed the QueryParser to handle escaped characters within quoted terms correctly.
  (Tomer Gabel via Michael Busch)
12. LUCENE-1299: Fixed NPE in SpellChecker when IndexReader is not null and field is
  (Grant Ingersoll)
13. LUCENE-1303: Fixed BoostingTermQuery's explanation to be marked as a Match depending only upon the non-payload score part, regardless of the effect of the payload on the score. Prior to this, score of a query containing a BTQ differed from its explanation.
  (Doron Cohen)
14. LUCENE-1310: Fixed SloppyPhraseScorer to work also for terms repeating more than twice in the query.
  (Doron Cohen)
15. LUCENE-1351: ISOLatin1AccentFilter now cleans additional ligatures
  (Cedrik Lime via Grant Ingersoll)
16. LUCENE-1383: Workaround a nasty "leak" in Java's builtin ThreadLocal, to prevent Lucene from causing unexpected OutOfMemoryError in certain situations (notably J2EE applications).
  (Chris Lu via Mike McCandless)
New features (20)
1. LUCENE-1137: Added Token.set/getFlags() accessors for passing more information about a Token through the analysis process. The flag is not indexed/stored and is thus only used by analysis.
2. LUCENE-1147: Add -segment option to CheckIndex tool so you can check only a specific segment or segments in your index.
  (Mike McCandless)
3. LUCENE-1045: Reopened this issue to add support for short and bytes.
4. LUCENE-584: Added new data structures to o.a.l.util, such as OpenBitSet and SortedVIntList. These extend DocIdSet and can directly be used for Filters with the new Filter API. Also changed the core Filters to use OpenBitSet instead of java.util.BitSet.
  (Paul Elschot, Michael Busch)
5. LUCENE-494: Added QueryAutoStopWordAnalyzer to allow for the automatic removal, from a query of frequently occurring terms. This Analyzer is not intended for use during indexing.
  (Mark Harwood via Grant Ingersoll)
6. LUCENE-1044: Change Lucene to properly "sync" files after committing, to ensure on a machine or OS crash or power cut, even with cached writes, the index remains consistent. Also added explicit commit() method to IndexWriter to force a commit without having to close.
  (Mike McCandless)
7. LUCENE-997: Add search timeout (partial) support. A TimeLimitedCollector was added to allow limiting search time. It is a partial solution since timeout is checked only when collecting a hit, and therefore a search for rare words in a huge index might not stop within the specified time.
  (Sean Timm via Doron Cohen)
8. LUCENE-1184: Allow SnapshotDeletionPolicy to be re-used across close/re-open of IndexWriter while still protecting an open snapshot
  (Tim Brennan via Mike McCandless)
9. LUCENE-1194: Added IndexWriter.deleteDocuments(Query) to delete documents matching the specified query. Also added static unlock and isLocked methods (deprecating the ones in IndexReader).
  (Mike McCandless)
10. LUCENE-1201: Add IndexReader.getIndexCommit() method.
  (Tim Brennan via Mike McCandless)
11. LUCENE-550: Added InstantiatedIndex implementation. Experimental Index store similar to MemoryIndex but allows for multiple documents in memory.
  (Karl Wettin via Grant Ingersoll)
12. LUCENE-400: Added word based n-gram filter (in contrib/analyzers) called ShingleFilter and an Analyzer wrapper that wraps another Analyzer's token stream with a ShingleFilter
  (Sebastian Kirsch, Steve Rowe via Grant Ingersoll)
13. LUCENE-1166: Decomposition tokenfilter for languages like German and Swedish
  (Thomas Peuss via Grant Ingersoll)
14. LUCENE-1187: ChainedFilter and BooleanFilter now work with new Filter API and DocIdSetIterator-based filters. Backwards-compatibility with old BitSet-based filters is ensured.
  (Paul Elschot via Michael Busch)
15. LUCENE-1295: Added new method to MoreLikeThis for retrieving interesting terms and made retrieveTerms(int) public.
  (Grant Ingersoll)
16. LUCENE-1298: MoreLikeThis can now accept a custom Similarity
  (Grant Ingersoll)
17. LUCENE-1297: Allow other string distance measures for the SpellChecker
  (Thomas Morton via Otis Gospodnetic)
18. LUCENE-1001: Provide access to Payloads via Spans. All existing Span Query implementations in Lucene implement.
  (Mark Miller, Grant Ingersoll)
19. LUCENE-1354: Provide programmatic access to CheckIndex
  (Grant Ingersoll, Mike McCandless)
20. LUCENE-1279: Add support for Collators to RangeFilter/Query and Query Parser.
  (Steve Rowe via Grant Ingersoll)
Optimizations (6)
1. LUCENE-705: When building a compound file, use RandomAccessFile.setLength() to tell the OS/filesystem to pre-allocate space for the file. This may improve fragmentation in how the CFS file is stored, and allows us to detect an upcoming disk full situation before actually filling up the disk.
  (Mike McCandless)
2. LUCENE-1120: Speed up merging of term vectors by bulk-copying the raw bytes for each contiguous range of non-deleted documents.
  (Mike McCandless)
3. LUCENE-1185: Avoid checking if the TermBuffer 'scratch' in SegmentTermEnum is null for every call of scanTo().
  (Christian Kohlschuetter via Michael Busch)
4. LUCENE-1217: Internal to Field.java, use isBinary instead of runtime type checking for possible speedup of binaryValue().
  (Eks Dev via Mike McCandless)
5. LUCENE-1183: Optimized TRStringDistance class (in contrib/spell) that uses less memory than the previous version.
  (Cédrik LIME via Otis Gospodnetic)
6. LUCENE-1195: Improve term lookup performance by adding a LRU cache to the TermInfosReader. In performance experiments the speedup was about 25% on average on mid-size indexes with ~500,000 documents for queries with 3 terms and about 7% on larger indexes with ~4.3M documents.
  (Michael Busch)
Documentation (4)
1. LUCENE-1236: Added some clarifying remarks to EdgeNGram*.java
  (Hiroaki Kawai via Grant Ingersoll)
2. LUCENE-1157 and LUCENE-1256: HTML changes log, created automatically from CHANGES.txt. This HTML file is currently visible only via developers page.
  (Steven Rowe via Doron Cohen)
3. LUCENE-1349: Fieldable can now be changed without breaking backward compatibility rules (within reason. See the note at the top of this file and also on Fieldable.java).
  (Grant Ingersoll)
4. LUCENE-1873: Update documentation to reflect current Contrib area status.
  (Steven Rowe, Mark Miller)
Build (3)
1. LUCENE-1153: Added JUnit JAR to new lib directory. Updated build to rely on local JUnit instead of ANT/lib.
2. LUCENE-1202: Small fixes to the way Clover is used to work better with contribs. Of particular note: a single clover db is used regardless of whether tests are run globally or in the specific contrib directories.
3. LUCENE-1353: Javacc target in contrib/miscellaneous for generating the precedence query parser.
Test Cases (2)
1. LUCENE-1238: Fixed intermittent failures of TestTimeLimitedCollector.testTimeoutMultiThreaded. Within this fix, "greedy" flag was added to TimeLimitedCollector, to allow the wrapped collector to collect also the last doc, after allowed-tTime passed.
  (Doron Cohen)
2. LUCENE-1348: relax TestTimeLimitedCollector to not fail due to timeout exceeded (just because test machine is very busy).

Release 2.3.2 [2008-05-06]

Bug fixes (12)
1. LUCENE-1191: On hitting OutOfMemoryError in any index-modifying methods in IndexWriter, do not commit any further changes to the index to prevent risk of possible corruption.
  (Mike McCandless)
2. LUCENE-1197: Fixed issue whereby IndexWriter would flush by RAM too early when TermVectors were in use.
  (Mike McCandless)
3. LUCENE-1198: Don't corrupt index if an exception happens inside DocumentsWriter.init
  (Mike McCandless)
4. LUCENE-1199: Added defensive check for null indexReader before calling close in IndexModifier.close()
  (Mike McCandless)
5. LUCENE-1200: Fix rare deadlock case in addIndexes* when ConcurrentMergeScheduler is in use
  (Mike McCandless)
6. LUCENE-1208: Fix deadlock case on hitting an exception while processing a document that had triggered a flush
  (Mike McCandless)
7. LUCENE-1210: Fix deadlock case on hitting an exception while starting a merge when using ConcurrentMergeScheduler
  (Mike McCandless)
8. LUCENE-1222: Fix IndexWriter.doAfterFlush to always be called on flush
  (Mark Ferguson via Mike McCandless)
9. LUCENE-1226: Fixed IndexWriter.addIndexes(IndexReader[]) to commit successfully created compound files.
  (Michael Busch)
10. LUCENE-1150: Re-expose StandardTokenizer's constants publicly; this was accidentally lost with LUCENE-966.
  (Nicolas Lalevée via Mike McCandless)
11. LUCENE-1262: Fixed bug in BufferedIndexReader.refill whereby on hitting an exception in readInternal, the buffer is incorrectly filled with stale bytes such that subsequent calls to readByte() return incorrect results.
  (Trejkaz via Mike McCandless)
12. LUCENE-1270: Fixed intermittent case where IndexWriter.close() would hang after IndexWriter.addIndexesNoOptimize had been called.
  (Stu Hood via Mike McCandless)
Build (1)
1. LUCENE-1230: Include *pom.xml* in source release files.
  (Michael Busch)

Release 2.3.1 [2008-02-22]

Bug fixes (7)
1. LUCENE-1168: Fixed corruption cases when autoCommit=false and documents have mixed term vectors
  (Suresh Guvvala via Mike McCandless).
2. LUCENE-1171: Fixed some cases where OOM errors could cause deadlock in IndexWriter
  (Mike McCandless).
3. LUCENE-1173: Fixed corruption case when autoCommit=false and bulk merging of stored fields is used
  (Yonik via Mike McCandless).
4. LUCENE-1163: Fixed bug in CharArraySet.contains(char[] buffer, int offset, int len) that was ignoring offset and thus giving the wrong answer.
  (Thomas Peuss via Mike McCandless)
5. LUCENE-1177: Fix rare case where IndexWriter.optimize might do too many merges at the end.
  (Mike McCandless)
6. LUCENE-1176: Fix corruption case when documents with no term vector fields are added before documents with term vector fields.
  (Mike McCandless)
7. LUCENE-1179: Fixed assert statement that was incorrectly preventing Fields with empty-string field name from working.
  (Sergey Kabashnyuk via Mike McCandless)

Release 2.3.0 [2008-01-23]

Changes in runtime behavior (2)
1. LUCENE-994: Defaults for IndexWriter have been changed to maximize out-of-the-box indexing speed. First, IndexWriter now flushes by RAM usage (16 MB by default) instead of a fixed doc count (call IndexWriter.setMaxBufferedDocs to get backwards compatible behavior). Second, ConcurrentMergeScheduler is used to run merges using background threads (call IndexWriter.setMergeScheduler(new SerialMergeScheduler()) to get backwards compatible behavior). Third, merges are chosen based on size in bytes of each segment rather than document count of each segment (call IndexWriter.setMergePolicy(new LogDocMergePolicy()) to get backwards compatible behavior).
  NOTE: users of ParallelReader must change back all of these defaults in order to ensure the docIDs "align" across all parallel indices.
  (Mike McCandless)
2. LUCENE-1045: SortField.AUTO didn't work with long. When detecting the field type for sorting automatically, numbers used to be interpreted as int, then as float, if parsing the number as an int failed. Now the detection checks for int, then for long, then for float.
  (Daniel Naber)
API Changes (14)
1. LUCENE-843: Added IndexWriter.setRAMBufferSizeMB(...) to have IndexWriter flush whenever the buffered documents are using more than the specified amount of RAM. Also added new APIs to Token that allow one to set a char[] plus offset and length to specify a token (to avoid creating a new String() for each Token).
  (Mike McCandless)
2. LUCENE-963: Add setters to Field to allow for re-using a single Field instance during indexing. This is a sizable performance gain, especially for small documents.
  (Mike McCandless)
3. LUCENE-969: Add new APIs to Token, TokenStream and Analyzer to permit re-using of Token and TokenStream instances during indexing. Changed Token to use a char[] as the store for the termText instead of String. This gives faster tokenization performance (~10-15%).
  (Mike McCandless)
4. LUCENE-847: Factored MergePolicy, which determines which merges should take place and when, as well as MergeScheduler, which determines when the selected merges should actually run, out of IndexWriter. The default merge policy is now LogByteSizeMergePolicy (see LUCENE-845) and the default merge scheduler is now ConcurrentMergeScheduler (see LUCENE-870).
  (Steven Parkes via Mike McCandless)
5. LUCENE-1052: Add IndexReader.setTermInfosIndexDivisor(int) method that allows you to reduce memory usage of the termInfos by further sub-sampling (over the termIndexInterval that was used during indexing) which terms are loaded into memory.
  (Chuck Williams, Doug Cutting via Mike McCandless)
6. LUCENE-743: Add IndexReader.reopen() method that re-opens an existing IndexReader (see New features -> 8.)
  (Michael Busch)
7. LUCENE-1062: Add setData(byte[] data), setData(byte[] data, int offset, int length), getData(), getOffset() and clone() methods to o.a.l.index.Payload. Also add the field name as arg to Similarity.scorePayload().
  (Michael Busch)
8. LUCENE-982: Add IndexWriter.optimize(int maxNumSegments) method to "partially optimize" an index down to maxNumSegments segments.
  (Mike McCandless)
9. LUCENE-1080: Changed Token.DEFAULT_TYPE to be public.
10. LUCENE-1064: Changed TopDocs constructor to be public.
  (Shai Erera via Michael Busch)
11. LUCENE-1079: DocValues cleanup: constructor now has no params, and getInnerArray() now throws UnsupportedOperationException
  (Doron Cohen)
12. LUCENE-1089: Added PriorityQueue.insertWithOverflow, which returns the Object (if any) that was bumped from the queue to allow re-use.
  (Shai Erera via Mike McCandless)
13. LUCENE-1101: Token reuse 'contract' (defined LUCENE-969) modified so it is token producer's responsibility to call Token.clear().
  (Doron Cohen)
14. LUCENE-1118: Changed StandardAnalyzer to skip too-long (default > 255 characters) tokens. You can increase this limit by calling StandardAnalyzer.setMaxTokenLength(...).
  (Michael McCandless)
Bug fixes (28)
1. LUCENE-933: QueryParser fixed to not produce empty sub BooleanQueries "()" even if the Analyzer produced no tokens for input.
  (Doron Cohen)
2. LUCENE-955: Fixed SegmentTermPositions to work correctly with the first term in the dictionary.
  (Michael Busch)
3. LUCENE-951: Fixed NullPointerException in MultiLevelSkipListReader that was thrown after a call of TermPositions.seek().
  (Rich Johnson via Michael Busch)
4. LUCENE-938: Fixed cases where an unhandled exception in IndexWriter's methods could cause deletes to be lost.
  (Steven Parkes via Mike McCandless)
5. LUCENE-962: Fixed case where an unhandled exception in IndexWriter.addDocument or IndexWriter.updateDocument could cause unreferenced files in the index to not be deleted
  (Steven Parkes via Mike McCandless)
6. LUCENE-957: RAMDirectory fixed to properly handle directories larger than Integer.MAX_VALUE.
  (Doron Cohen)
7. LUCENE-781: MultiReader fixed to not throw NPE if isCurrent(), isOptimized() or getVersion() is called. Separated MultiReader into two classes: MultiSegmentReader extends IndexReader, is package-protected and is created automatically by IndexReader.open() in case the index has multiple segments. The public MultiReader now extends MultiSegmentReader and is intended to be used by users who want to add their own subreaders.
  (Daniel Naber, Michael Busch)
8. LUCENE-970: FilterIndexReader now implements isOptimized(). Before a call of isOptimized() would throw a NPE.
  (Michael Busch)
9. LUCENE-832: ParallelReader fixed to not throw NPE if isCurrent(), isOptimized() or getVersion() is called.
  (Michael Busch)
10. LUCENE-948: Fix FNFE exception caused by stale NFS client directory listing caches when writers on different machines are sharing an index over NFS and using a custom deletion policy
  (Mike McCandless)
11. LUCENE-978: Ensure TermInfosReader, FieldsReader, and FieldsReader close any streams they had opened if an exception is hit in the constructor.
  (Ning Li via Mike McCandless)
12. LUCENE-985: If an extremely long term is in a doc (> 16383 chars), we now throw an IllegalArgumentException saying the term is too long, instead of cryptic ArrayIndexOutOfBoundsException.
  (Karl Wettin via Mike McCandless)
13. LUCENE-991: The explain() method of BoostingTermQuery had errors when no payloads were present on a document.
  (Peter Keegan via Grant Ingersoll)
14. LUCENE-992: Fixed IndexWriter.updateDocument to be atomic again (this was broken by LUCENE-843).
  (Ning Li via Mike McCandless)
15. LUCENE-1008: Fixed corruption case when document with no term vector fields is added after documents with term vector fields. This bug was introduced with LUCENE-843.
  (Grant Ingersoll via Mike McCandless)
16. LUCENE-1006: Fixed QueryParser to accept a "" field value (zero length quoted string.)
  (yonik)
17. LUCENE-1010: Fixed corruption case when document with no term vector fields is added after documents with term vector fields. This case is hit during merge and would cause an EOFException. This bug was introduced with LUCENE-984.
  (Andi Vajda via Mike McCandless)
18. LUCENE-1009: Fix merge slowdown with LogByteSizeMergePolicy when autoCommit=false and documents are using stored fields and/or term vectors.
  (Mark Miller via Mike McCandless)
19. LUCENE-1011: Fixed corruption case when two or more machines, sharing an index over NFS, can be writers in quick succession.
  (Patrick Kimber via Mike McCandless)
20. LUCENE-1028: Fixed Weight serialization for few queries: DisjunctionMaxQuery, ValueSourceQuery, CustomScoreQuery. Serialization check added for all queries.
  (Kyle Maxwell via Doron Cohen)
21. LUCENE-1048: Fixed incorrect behavior in Lock.obtain(...) when the timeout argument is very large (eg Long.MAX_VALUE). Also added Lock.LOCK_OBTAIN_WAIT_FOREVER constant to never timeout.
  (Nikolay Diakov via Mike McCandless)
22. LUCENE-1050: Throw LockReleaseFailedException in Simple/NativeFSLockFactory if we fail to delete the lock file when releasing the lock.
  (Nikolay Diakov via Mike McCandless)
23. LUCENE-1071: Fixed SegmentMerger to correctly set payload bit in the merged segment.
  (Michael Busch)
24. LUCENE-1042: Remove throwing of IOException in getTermFreqVector(int, String, TermVectorMapper) to be consistent with other getTermFreqVector calls. Also removed the throwing of the other IOException in that method to be consistent.
  (Karl Wettin via Grant Ingersoll)
25. LUCENE-1096: Fixed Hits behavior when hits' docs are deleted along with iterating the hits. Deleting docs already retrieved now works seamlessly. If docs not yet retrieved are deleted (e.g. from another thread), and then, relying on the initial Hits.length(), an application attempts to retrieve more hits than actually exist , a ConcurrentMidificationException is thrown.
  (Doron Cohen)
26. LUCENE-1068: Changed StandardTokenizer to fix an issue with it marking the type of some tokens incorrectly. This is done by adding a new flag named replaceInvalidAcronym which defaults to false, the current, incorrect behavior. Setting this flag to true fixes the problem. This flag is a temporary fix and is already marked as being deprecated. 3.x will implement the correct approach. (Shai Erera via Grant Ingersoll) LUCENE-1140: Fixed NPE caused by 1068
  (Alexei Dets via Grant Ingersoll)
27. LUCENE-749: ChainedFilter behavior fixed when logic of first filter is ANDNOT.
  (Antonio Bruno via Doron Cohen)
28. LUCENE-508: Make sure SegmentTermEnum.prev() is accurate (= last term) after next() returns false.
  (Steven Tamm via Mike McCandless)
New features (14)
1. LUCENE-906: Elision filter for French.
  (Mathieu Lecarme via Otis Gospodnetic)
2. LUCENE-960: Added a SpanQueryFilter and related classes to allow for not only filtering, but knowing where in a Document a Filter matches
  (Grant Ingersoll)
3. LUCENE-868: Added new Term Vector access features. New callback mechanism allows application to define how and where to read Term Vectors from disk. This implementation contains several extensions of the new abstract TermVectorMapper class. The new API should be back-compatible. No changes in the actual storage of Term Vectors has taken place.
4. LUCENE-1038: Added setDocumentNumber() method to TermVectorMapper to provide information about what document is being accessed.
  (Karl Wettin via Grant Ingersoll)
5. LUCENE-975: Added PositionBasedTermVectorMapper that allows for position based lookup of term vector information. See item #3 above (LUCENE-868).
6. LUCENE-1011: Added simple tools (all in org.apache.lucene.store) to verify that locking is working properly. LockVerifyServer runs a separate server to verify locks. LockStressTest runs a simple tool that rapidly obtains and releases locks. VerifyingLockFactory is a LockFactory that wraps any other LockFactory and consults the LockVerifyServer whenever a lock is obtained or released, throwing an exception if an illegal lock obtain occurred.
  (Patrick Kimber via Mike McCandless)
7. LUCENE-1015: Added FieldCache extension (ExtendedFieldCache) to support doubles and longs. Added support into SortField for sorting on doubles and longs as well.
  (Grant Ingersoll)
8. LUCENE-1020: Created basic index checking & repair tool (o.a.l.index.CheckIndex). When run without -fix it does a detailed test of all segments in the index and reports summary information and any errors it hit. With -fix it will remove segments that had errors.
  (Mike McCandless)
9. LUCENE-743: Add IndexReader.reopen() method that re-opens an existing IndexReader by only loading those portions of an index that have changed since the reader was (re)opened. reopen() can be significantly faster than open(), depending on the amount of index changes. SegmentReader, MultiSegmentReader, MultiReader, and ParallelReader implement reopen().
  (Michael Busch)
10. LUCENE-1040: CharArraySet useful for efficiently checking set membership of text specified by char[].
  (yonik)
11. LUCENE-1073: Created SnapshotDeletionPolicy to facilitate taking a live backup of an index without pausing indexing.
  (Mike McCandless)
12. LUCENE-1019: CustomScoreQuery enhanced to support multiple ValueSource queries.
  (Kyle Maxwell via Doron Cohen)
13. LUCENE-1095: Added an option to StopFilter to increase positionIncrement of the token succeeding a stopped token. Disabled by default. Similar option added to QueryParser to consider token positions when creating PhraseQuery and MultiPhraseQuery. Disabled by default (so by default the query parser ignores position increments).
  (Doron Cohen)
14. LUCENE-1380: Added TokenFilter for setting position increment in special cases related to the ShingleFilter
  (Mck SembWever, Steve Rowe, Karl Wettin via Grant Ingersoll)
Optimizations (14)
1. LUCENE-937: CachingTokenFilter now uses an iterator to access the Tokens that are cached in the LinkedList. This increases performance significantly, especially when the number of Tokens is large.
  (Mark Miller via Michael Busch)
2. LUCENE-843: Substantial optimizations to improve how IndexWriter uses RAM for buffering documents and to speed up indexing (2X-8X faster). A single shared hash table now records the in-memory postings per unique term and is directly flushed into a single segment.
  (Mike McCandless)
3. LUCENE-892: Fixed extra "buffer to buffer copy" that sometimes takes place when using compound files.
  (Mike McCandless)
4. LUCENE-959: Remove synchronization in Document
  (yonik)
5. LUCENE-963: Add setters to Field to allow for re-using a single Field instance during indexing. This is a sizable performance gain, especially for small documents.
  (Mike McCandless)
6. LUCENE-939: Check explicitly for boundary conditions in FieldInfos and don't rely on exceptions.
  (Michael Busch)
7. LUCENE-966: Very substantial speedups (~6X faster) for StandardTokenizer (StandardAnalyzer) by using JFlex instead of JavaCC to generate the tokenizer.
  (Stanislaw Osinski via Mike McCandless)
8. LUCENE-969: Changed core tokenizers & filters to re-use Token and TokenStream instances when possible to improve tokenization performance (~10-15%).
  (Mike McCandless)
9. LUCENE-871: Speedup ISOLatin1AccentFilter
  (Ian Boston via Mike McCandless)
10. LUCENE-986: Refactored SegmentInfos from IndexReader into the new subclass DirectoryIndexReader. SegmentReader and MultiSegmentReader now extend DirectoryIndexReader and are the only IndexReader implementations that use SegmentInfos to access an index and acquire a write lock for index modifications.
  (Michael Busch)
11. LUCENE-1007: Allow flushing in IndexWriter to be triggered by either RAM usage or document count or both (whichever comes first), by adding symbolic constant DISABLE_AUTO_FLUSH to disable one of the flush triggers.
  (Ning Li via Mike McCandless)
12. LUCENE-1043: Speed up merging of stored fields by bulk-copying the raw bytes for each contiguous range of non-deleted documents.
  (Robert Engels via Mike McCandless)
13. LUCENE-693: Speed up nested conjunctions (~2x) that match many documents, and a slight performance increase for top level conjunctions.
  (yonik)
14. LUCENE-1098: Make inner class StandardAnalyzer.SavedStreams static and final.
  (Nathan Beyer via Michael Busch)
Documentation (2)
1. LUCENE-1051: Generate separate javadocs for core, demo and contrib classes, as well as an unified view. Also add an appropriate menu structure to the website.
  (Michael Busch)
2. LUCENE-746: Fix error message in AnalyzingQueryParser.getPrefixQuery.
  (Ronnie Kolehmainen via Michael Busch)
Build (8)
1. LUCENE-908: Improvements and simplifications for how the MANIFEST file and the META-INF dir are created.
  (Michael Busch)
2. LUCENE-935: Various improvements for the maven artifacts. Now the artifacts also include the sources as .jar files.
  (Michael Busch)
3. Added apply-patch target to top-level build. Defaults to looking for a patch in ${basedir}/../patches with name specified by -Dpatch.name. Can also specify any location by -Dpatch.file property on the command line. This should be helpful for easy application of patches, but it is also a step towards integrating automatic patch application with JIRA and Hudson, and is thus subject to change.
  (Grant Ingersoll)
4. LUCENE-935: Defined property "m2.repository.url" to allow setting the url to a maven remote repository to deploy to.
  (Michael Busch)
5. LUCENE-1051: Include javadocs in the maven artifacts.
  (Michael Busch)
6. LUCENE-1055: Remove gdata-server from build files and its sources from trunk.
  (Michael Busch)
7. LUCENE-935: Allow to deploy maven artifacts to a remote m2 repository via scp and ssh authentication.
  (Michael Busch)
8. LUCENE-1123: Allow overriding the specification version for MANIFEST.MF
  (Michael Busch)
Test Cases (1)
1. LUCENE-766: Test adding two fields with the same name but different term vector setting.
  (Nicolas Lalevée via Doron Cohen)

Release 2.2.0 [2007-06-19]

Changes in runtime behavior (none)
API Changes (13)
1. LUCENE-793: created new exceptions and added them to throws clause for many methods (all subclasses of IOException for backwards compatibility): index.StaleReaderException, index.CorruptIndexException, store.LockObtainFailedException. This was done to better call out the possible root causes of an IOException from these methods.
  (Mike McCandless)
2. LUCENE-811: make SegmentInfos class, plus a few methods from related classes, package-private again (they were unnecessarily made public as part of LUCENE-701).
  (Mike McCandless)
3. LUCENE-710: added optional autoCommit boolean to IndexWriter constructors. When this is false, index changes are not committed until the writer is closed. This gives explicit control over when a reader will see the changes. Also added optional custom deletion policy to explicitly control when prior commits are removed from the index. This is intended to allow applications to share an index over NFS by customizing when prior commits are deleted.
  (Mike McCandless)
4. LUCENE-818: changed most public methods of IndexWriter, IndexReader (and its subclasses), FieldsReader and RAMDirectory to throw AlreadyClosedException if they are accessed after being closed.
  (Mike McCandless)
5. LUCENE-834: Changed some access levels for certain Span classes to allow them to be overridden. They have been marked expert only and not for public consumption.
  (Grant Ingersoll)
6. LUCENE-796: Removed calls to super.* from various get*Query methods in MultiFieldQueryParser, in order to allow sub-classes to override them.
  (Steven Parkes via Otis Gospodnetic)
7. LUCENE-857: Removed caching from QueryFilter and deprecated QueryFilter in favour of QueryWrapperFilter or QueryWrapperFilter + CachingWrapperFilter combination when caching is desired.
  (Chris Hostetter, Otis Gospodnetic)
8. LUCENE-869: Changed FSIndexInput and FSIndexOutput to inner classes of FSDirectory to enable extensibility of these classes.
  (Michael Busch)
9. LUCENE-580: Added the public method reset() to TokenStream. This method does nothing by default, but may be overwritten by subclasses to support consuming the TokenStream more than once.
  (Michael Busch)
10. LUCENE-580: Added a new constructor to Field that takes a TokenStream as argument, available as tokenStreamValue(). This is useful to avoid the need of "dummy analyzers" for pre-analyzed fields.
  (Karl Wettin, Michael Busch)
11. LUCENE-730: Added the new methods to BooleanQuery setAllowDocsOutOfOrder() and getAllowDocsOutOfOrder(). Deprecated the methods setUseScorer14() and getUseScorer14(). The optimization patch LUCENE-730 (see Optimizations->3.) improves performance for certain queries but results in scoring out of docid order. This patch reverse this change, so now by default hit docs are scored in docid order if not setAllowDocsOutOfOrder(true) is explicitly called. This patch also enables the tests in QueryUtils again that check for docid order.
  (Paul Elschot, Doron Cohen, Michael Busch)
12. LUCENE-888: Added Directory.openInput(File path, int bufferSize) to optionally specify the size of the read buffer. Also added BufferedIndexInput.setBufferSize(int) to change the buffer size.
  (Mike McCandless)
13. LUCENE-923: Make SegmentTermPositionVector package-private. It does not need to be public because it implements the public interface TermPositionVector.
  (Michael Busch)
Bug fixes (24)
1. LUCENE-804: Fixed build.xml to pack a fully compilable src dist.
  (Doron Cohen)
2. LUCENE-813: Leading wildcard fixed to work with trailing wildcard. Query parser modified to create a prefix query only for the case that there is a single trailing wildcard (and no additional wildcard or '?' in the query text).
  (Doron Cohen)
3. LUCENE-812: Add no-argument constructors to NativeFSLockFactory and SimpleFSLockFactory. This enables all 4 builtin LockFactory implementations to be specified via the System property org.apache.lucene.store.FSDirectoryLockFactoryClass.
  (Mike McCandless)
4. LUCENE-821: The new single-norm-file introduced by LUCENE-756 failed to reduce the number of open descriptors since it was still opened once per field with norms.
  (yonik)
5. LUCENE-823: Make sure internal file handles are closed when hitting an exception (eg disk full) while flushing deletes in IndexWriter's mergeSegments, and also during IndexWriter.addIndexes.
  (Mike McCandless)
6. LUCENE-825: If directory is removed after FSDirectory.getDirectory() but before IndexReader.open you now get a FileNotFoundException like Lucene pre-2.1 (before this fix you got an NPE).
  (Mike McCandless)
7. LUCENE-800: Removed backslash from the TERM_CHAR list in the queryparser, because the backslash is the escape character. Also changed the ESCAPED_CHAR list to contain all possible characters, because every character that follows a backslash should be considered as escaped.
  (Michael Busch)
8. LUCENE-372: QueryParser.parse() now ensures that the entire input string is consumed. Now a ParseException is thrown if a query contains too many closing parentheses.
  (Andreas Neumann via Michael Busch)
9. LUCENE-814: javacc build targets now fix line-end-style of generated files. Now also deleting all javacc generated files before calling javacc.
  (Steven Parkes, Doron Cohen)
10. LUCENE-829: close readers in contrib/benchmark.
  (Karl Wettin, Doron Cohen)
11. LUCENE-828: Minor fix for Term's equal().
  (Paul Cowan via Otis Gospodnetic)
12. LUCENE-846: Fixed: if IndexWriter is opened with autoCommit=false, and you call addIndexes, and hit an exception (eg disk full) then when IndexWriter rolls back its internal state this could corrupt the instance of IndexWriter (but, not the index itself) by referencing already deleted segments. This bug was only present in 2.2 (trunk), ie was never released.
  (Mike McCandless)
13. LUCENE-736: Sloppy phrase query with repeating terms matches wrong docs. For example query "B C B"~2 matches the doc "A B C D E".
  (Doron Cohen)
14. LUCENE-789: Fixed: custom similarity is ignored when using MultiSearcher (problem reported by Alexey Lef). Now the similarity applied by MultiSearcer.setSimilarity(sim) is being used. Note that as before this fix, creating a multiSearcher from Searchers for whom custom similarity was set has no effect - it is masked by the similarity of the MultiSearcher. This is as designed, because MultiSearcher operates on Searchables (not Searchers).
  (Doron Cohen)
15. LUCENE-880: Fixed DocumentWriter to close the TokenStreams after it has written the postings. Then the resources associated with the TokenStreams can safely be released.
  (Michael Busch)
16. LUCENE-883: consecutive calls to Spellchecker.indexDictionary() won't insert terms twice anymore.
  (Daniel Naber)
17. LUCENE-881: QueryParser.escape() now also escapes the characters '|' and '&' which are part of the queryparser syntax.
  (Michael Busch)
18. LUCENE-886: Spellchecker clean up: exceptions aren't printed to STDERR anymore and ignored, but re-thrown. Some javadoc improvements.
  (Daniel Naber)
19. LUCENE-698: FilteredQuery now takes the query boost into account for scoring.
  (Michael Busch)
20. LUCENE-763: Spellchecker: LuceneDictionary used to skip first word in enumeration.
  (Christian Mallwitz via Daniel Naber)
21. LUCENE-903: FilteredQuery explanation inaccuracy with boost. Explanation tests now "deep" check the explanation details.
  (Chris Hostetter, Doron Cohen)
22. LUCENE-912: DisjunctionMaxScorer first skipTo(target) call ignores the skip target param and ends up at the first match.
  (Sudaakeran B. via Chris Hostetter & Doron Cohen)
23. LUCENE-913: Two consecutive score() calls return different scores for Boolean Queries.
  (Michael Busch, Doron Cohen)
24. LUCENE-1013: Fix IndexWriter.setMaxMergeDocs to work "out of the box", again, by moving set/getMaxMergeDocs up from LogDocMergePolicy into LogMergePolicy. This fixes the API breakage (non backwards compatible change) caused by LUCENE-994.
  (Yonik Seeley via Mike McCandless)
New features (9)
1. LUCENE-759: Added two n-gram-producing TokenFilters.
  (Otis Gospodnetic)
2. LUCENE-822: Added FieldSelector capabilities to Searchable for use with RemoteSearcher, and other Searchable implementations.
  (Mark Miller, Grant Ingersoll)
3. LUCENE-755: Added the ability to store arbitrary binary metadata in the posting list. These metadata are called Payloads. For every position of a Token one Payload in the form of a variable length byte array can be stored in the prox file. Remark: The APIs introduced with this feature are in experimental state and thus contain appropriate warnings in the javadocs.
  (Michael Busch)
4. LUCENE-834: Added BoostingTermQuery which can boost scores based on the values of a payload (see #3 above.)
  (Grant Ingersoll)
5. LUCENE-834: Similarity has a new method for scoring payloads called scorePayloads that can be overridden to take advantage of payload storage (see #3 above)
6. LUCENE-834: Added isPayloadAvailable() onto TermPositions interface and implemented it in the appropriate places
  (Grant Ingersoll)
7. LUCENE-853: Added RemoteCachingWrapperFilter to enable caching of Filters on the remote side of the RMI connection.
  (Matt Ericson via Otis Gospodnetic)
8. LUCENE-446: Added Solr's search.function for scores based on field values, plus CustomScoreQuery for simple score (post) customization.
  (Yonik Seeley, Doron Cohen)
9. LUCENE-1058: Added new TeeTokenFilter (like the UNIX 'tee' command) and SinkTokenizer which can be used to share tokens between two or more Fields such that the other Fields do not have to go through the whole Analysis process over again. For instance, if you have two Fields that share all the same analysis steps except one lowercases tokens and the other does not, you can coordinate the operations between the two using the TeeTokenFilter and the SinkTokenizer. See TeeSinkTokenTest.java for examples.
  (Grant Ingersoll, Michael Busch, Yonik Seeley)
Optimizations (7)
1. LUCENE-761: The proxStream is now cloned lazily in SegmentTermPositions when nextPosition() is called for the first time. This allows using instances of SegmentTermPositions instead of SegmentTermDocs without additional costs.
  (Michael Busch)
2. LUCENE-431: RAMInputStream and RAMOutputStream extend IndexInput and IndexOutput directly now. This avoids further buffering and thus avoids unnecessary array copies.
  (Michael Busch)
3. LUCENE-730: Updated BooleanScorer2 to make use of BooleanScorer in some cases and possibly improve scoring performance. Documents can now be delivered out-of-order as they are scored (e.g. to HitCollector). N.B. A bit of code had to be disabled in QueryUtils in order for TestBoolean2 test to keep passing.
  (Paul Elschot via Otis Gospodnetic)
4. LUCENE-882: Spellchecker doesn't store the ngrams anymore but only indexes them to keep the spell index small.
  (Daniel Naber)
5. LUCENE-430: Delay allocation of the buffer after a clone of BufferedIndexInput. Together with LUCENE-888 this will allow to adjust the buffer size dynamically.
  (Paul Elschot, Michael Busch)
6. LUCENE-888: Increase buffer sizes inside CompoundFileWriter and BufferedIndexOutput. Also increase buffer size in BufferedIndexInput, but only when used during merging. Together, these increases yield 10-18% overall performance gain vs the previous 1K defaults.
  (Mike McCandless)
7. LUCENE-866: Adds multi-level skip lists to the posting lists. This speeds up most queries that use skipTo(), especially on big indexes with large posting lists. For average AND queries the speedup is about 20%, for queries that contain very frequent and very unique terms the speedup can be over 80%.
  (Michael Busch)
Documentation (6)
1. LUCENE 791 && INFRA-1173: Infrastructure moved the Wiki to http://wiki.apache.org/lucene-java/ Updated the links in the docs and wherever else I found references.
  (Grant Ingersoll, Joe Schaefer)
2. LUCENE-807: Fixed the javadoc for ScoreDocComparator.compare() to be consistent with java.util.Comparator.compare(): Any integer is allowed to be returned instead of only -1/0/1.
  (Paul Cowan via Michael Busch)
3. LUCENE-875: Solved javadoc warnings & errors under jdk1.4. Solved javadoc errors under jdk5 (jars in path for gdata). Made "javadocs" target depend on "build-contrib" for first downloading contrib jars configured for dynamic downloaded. (Note: when running behind firewall, a firewall prompt might pop up)
  (Doron Cohen)
4. LUCENE-740: Added SNOWBALL-LICENSE.txt to the snowball package and a remark about the license to NOTICE.TXT.
  (Steven Parkes via Michael Busch)
5. LUCENE-925: Added analysis package javadocs.
  (Grant Ingersoll and Doron Cohen)
6. LUCENE-926: Added document package javadocs.
  (Grant Ingersoll)
Build (10)
1. LUCENE-802: Added LICENSE.TXT and NOTICE.TXT to Lucene jars.
  (Steven Parkes via Michael Busch)
2. LUCENE-885: "ant test" now includes all contrib tests. The new "ant test-core" target can be used to run only the Core (non contrib) tests.
  (Chris Hostetter)
3. LUCENE-900: "ant test" now enables Java assertions (in Lucene packages).
  (Doron Cohen)
4. LUCENE-894: Add custom build file for binary distributions that includes targets to build the demos.
  (Chris Hostetter, Michael Busch)
5. LUCENE-904: The "package" targets in build.xml now also generate .md5 checksum files.
  (Chris Hostetter, Michael Busch)
6. LUCENE-907: Include LICENSE.TXT and NOTICE.TXT in the META-INF dirs of demo war, demo jar, and the contrib jars.
  (Michael Busch)
7. LUCENE-909: Demo targets for running the demo.
  (Doron Cohen)
8. LUCENE-908: Improves content of MANIFEST file and makes it customizable for the contribs. Adds SNOWBALL-LICENSE.txt to META-INF of the snowball jar and makes sure that the lucli jar contains LICENSE.txt and NOTICE.txt.
  (Chris Hostetter, Michael Busch)
9. LUCENE-930: Various contrib building improvements to ensure contrib dependencies are met, and test compilation errors fail the build.
  (Steven Parkes, Chris Hostetter)
10. LUCENE-622: Add ant target and pom.xml files for building maven artifacts of the Lucene core and the contrib modules.
  (Sami Siren, Karl Wettin, Michael Busch)

Release 2.1.0 [2007-02-17]

Changes in runtime behavior (9)
1. 's' and 't' have been removed from the list of default stopwords in StopAnalyzer (also used in by StandardAnalyzer). Having e.g. 's' as a stopword meant that 's-class' led to the same results as 'class'. Note that this problem still exists for 'a', e.g. in 'a-class' as 'a' continues to be a stopword.
  (Daniel Naber)
2. LUCENE-478: Updated the list of Unicode code point ranges for CJK (now split into CJ and K) in StandardAnalyzer.
  (John Wang and Steven Rowe via Otis Gospodnetic)
3. Modified some CJK Unicode code point ranges in StandardTokenizer.jj, and added a few more of them to increase CJK character coverage. Also documented some of the ranges.
  (Otis Gospodnetic)
4. LUCENE-489: Add support for leading wildcard characters (*, ?) to QueryParser. Default is to disallow them, as before.
  (Steven Parkes via Otis Gospodnetic)
5. LUCENE-703: QueryParser changed to default to use of ConstantScoreRangeQuery for range queries. Added useOldRangeQuery property to QueryParser to allow selection of old RangeQuery class if required.
  (Mark Harwood)
6. LUCENE-543: WildcardQuery now performs a TermQuery if the provided term does not contain a wildcard character (? or *), when previously a StringIndexOutOfBoundsException was thrown.
  (Michael Busch via Erik Hatcher)
7. LUCENE-726: Removed the use of deprecated doc.fields() method and Enumeration.
  (Michael Busch via Otis Gospodnetic)
8. LUCENE-436: Removed finalize() in TermInfosReader and SegmentReader, and added a call to enumerators.remove() in TermInfosReader.close(). The finalize() overrides were added to help with a pre-1.4.2 JVM bug that has since been fixed, plus we no longer support pre-1.4.2 JVMs.
  (Otis Gospodnetic)
9. LUCENE-771: The default location of the write lock is now the index directory, and is named simply "write.lock" (without a big digest prefix). The system properties "org.apache.lucene.lockDir" nor "java.io.tmpdir" are no longer used as the global directory for storing lock files, and the LOCK_DIR field of FSDirectory is now deprecated.
  (Mike McCandless)
New features (15)
1. LUCENE-503: New ThaiAnalyzer and ThaiWordFilter in contrib/analyzers
  (Samphan Raruenrom via Chris Hostetter)
2. LUCENE-545: New FieldSelector API and associated changes to IndexReader and implementations. New Fieldable interface for use with the lazy field loading mechanism.
  (Grant Ingersoll and Chuck Williams via Grant Ingersoll)
3. LUCENE-676: Move Solr's PrefixFilter to Lucene core.
  (Yura Smolsky, Yonik Seeley)
4. LUCENE-678: Added NativeFSLockFactory, which implements locking using OS native locking (via java.nio.*).
  (Michael McCandless via Yonik Seeley)
5. LUCENE-544: Added the ability to specify different boosts for different fields when using MultiFieldQueryParser
  (Matt Ericson via Otis Gospodnetic)
6. LUCENE-528: New IndexWriter.addIndexesNoOptimize() that doesn't optimize the index when adding new segments, only performing merges as needed.
  (Ning Li via Yonik Seeley)
7. LUCENE-573: QueryParser now allows backslash escaping in quoted terms and phrases.
  (Michael Busch via Yonik Seeley)
8. LUCENE-716: QueryParser now allows specification of Unicode characters in terms via a unicode escape of the form \uXXXX
  (Michael Busch via Yonik Seeley)
9. LUCENE-709: Added RAMDirectory.sizeInBytes(), IndexWriter.ramSizeInBytes() and IndexWriter.flushRamSegments(), allowing applications to control the amount of memory used to buffer documents.
  (Chuck Williams via Yonik Seeley)
10. LUCENE-723: QueryParser now parses *:* as MatchAllDocsQuery
  (Yonik Seeley)
11. LUCENE-741: Command-line utility for modifying or removing norms on fields in an existing index. This is mostly based on LUCENE-496 and lives in contrib/miscellaneous.
  (Chris Hostetter, Otis Gospodnetic)
12. LUCENE-759: Added NGramTokenizer and EdgeNGramTokenizer classes and their passing unit tests.
  (Otis Gospodnetic)
13. LUCENE-565: Added methods to IndexWriter to more efficiently handle updating documents (the "delete then add" use case). This is intended to be an eventual replacement for the existing IndexModifier. Added IndexWriter.flush() (renamed from flushRamSegments()) to flush all pending updates (held in RAM), to the Directory.
  (Ning Li via Mike McCandless)
14. LUCENE-762: Added in SIZE and SIZE_AND_BREAK FieldSelectorResult options which allow one to retrieve the size of a field without retrieving the actual field.
  (Chuck Williams via Grant Ingersoll)
15. LUCENE-799: Properly handle lazy, compressed fields.
  (Mike Klaas via Grant Ingersoll)
API Changes (19)
1. LUCENE-438: Remove "final" from Token, implement Cloneable, allow changing of termText via setTermText().
  (Yonik Seeley)
2. org.apache.lucene.analysis.nl.WordlistLoader has been deprecated and is supposed to be replaced with the WordlistLoader class in package org.apache.lucene.analysis
  (Daniel Naber)
3. LUCENE-609: Revert return type of Document.getField(s) to Field for backward compatibility, added new Document.getFieldable(s) for access to new lazy loaded fields.
  (Yonik Seeley)
4. LUCENE-608: Document.fields() has been deprecated and a new method Document.getFields() has been added that returns a List instead of an Enumeration
  (Daniel Naber)
5. LUCENE-605: New Explanation.isMatch() method and new ComplexExplanation subclass allows explain methods to produce Explanations which model "matching" independent of having a positive value.
  (Chris Hostetter)
6. LUCENE-621: New static methods IndexWriter.setDefaultWriteLockTimeout and IndexWriter.setDefaultCommitLockTimeout for overriding default timeout values for all future instances of IndexWriter (as well as for any other classes that may reference the static values, ie: IndexReader).
  (Michael McCandless via Chris Hostetter)
7. LUCENE-638: FSDirectory.list() now only returns the directory's Lucene-related files. Thanks to this change one can now construct a RAMDirectory from a file system directory that contains files not related to Lucene.
  (Simon Willnauer via Daniel Naber)
8. LUCENE-635: Decoupling locking implementation from Directory implementation. Added set/getLockFactory to Directory and moved all locking code into subclasses of abstract class LockFactory. FSDirectory and RAMDirectory still default to their prior locking implementations, but now you can mix & match, for example using SingleInstanceLockFactory (ie, in memory locking) locking with an FSDirectory. Note that now you must call setDisableLocks before the instantiation a FSDirectory if you wish to disable locking for that Directory.
  (Michael McCandless, Jeff Patterson via Yonik Seeley)
9. LUCENE-657: Made FuzzyQuery non-final and inner ScoreTerm protected.
  (Steven Parkes via Otis Gospodnetic)
10. LUCENE-701: Lockless commits: a commit lock is no longer required when a writer commits and a reader opens the index. This includes a change to the index file format (see docs/fileformats.html for details). It also removes all APIs associated with the commit lock & its timeout. Readers are now truly read-only and do not block one another on startup. This is the first step to getting Lucene to work correctly over NFS (second step is LUCENE-710).
  (Mike McCandless)
11. LUCENE-722: DEFAULT_MIN_DOC_FREQ was misspelled DEFALT_MIN_DOC_FREQ in Similarity's MoreLikeThis class. The misspelling has been replaced by the correct spelling.
  (Andi Vajda via Daniel Naber)
12. LUCENE-738: Reduce the size of the file that keeps track of which documents are deleted when the number of deleted documents is small. This changes the index file format and cannot be read by previous versions of Lucene.
  (Doron Cohen via Yonik Seeley)
13. LUCENE-756: Maintain all norms in a single .nrm file to reduce the number of open files and file descriptors for the non-compound index format. This changes the index file format, but maintains the ability to read and update older indices. The first segment merge on an older format index will create a single .nrm file for the new segment.
  (Doron Cohen via Yonik Seeley)
14. LUCENE-732: DateTools support has been added to QueryParser, with setters for both the default Resolution, and per-field Resolution. For backwards compatibility, DateField is still used if no Resolutions are specified.
  (Michael Busch via Chris Hostetter)
15. Added isOptimized() method to IndexReader.
  (Otis Gospodnetic)
16. LUCENE-773: Deprecate the FSDirectory.getDirectory(*) methods that take a boolean "create" argument. Instead you should use IndexWriter's "create" argument to create a new index.
  (Mike McCandless)
17. LUCENE-780: Add a static Directory.copy() method to copy files from one Directory to another.
  (Jiri Kuhn via Mike McCandless)
18. LUCENE-773: Added Directory.clearLock(String name) to forcefully remove an old lock. The default implementation is to ask the lockFactory (if non null) to clear the lock.
  (Mike McCandless)
19. LUCENE-795: Directory.renameFile() has been deprecated as it is not used anymore inside Lucene.
  (Daniel Naber)
Bug fixes (32)
1. Fixed the web application demo (built with "ant war-demo") which didn't work because it used a QueryParser method that had been removed
  (Daniel Naber)
2. LUCENE-583: ISOLatin1AccentFilter fails to preserve positionIncrement
  (Yonik Seeley)
3. LUCENE-575: SpellChecker min score is incorrectly changed by suggestSimilar
  (Karl Wettin via Yonik Seeley)
4. LUCENE-587: Explanation.toHtml was producing malformed HTML
  (Chris Hostetter)
5. Fix to allow MatchAllDocsQuery to be used with RemoteSearcher
  (Yonik Seeley)
6. LUCENE-601: RAMDirectory and RAMFile made Serializable
  (Karl Wettin via Otis Gospodnetic)
7. LUCENE-557: Fixes to BooleanQuery and FilteredQuery so that the score Explanations match up with the real scores.
  (Chris Hostetter)
8. LUCENE-607: ParallelReader's TermEnum fails to advance properly to new fields
  (Chuck Williams, Christian Kohlschuetter via Yonik Seeley)
9. LUCENE-610,LUCENE-611: Simple syntax changes to allow compilation with ecj: disambiguate inner class scorer's use of doc() in BooleanScorer2, other test code changes.
  (DM Smith via Yonik Seeley)
10. LUCENE-451: All core query types now use ComplexExplanations so that boosts of zero don't confuse the BooleanWeight explain method.
  (Chris Hostetter)
11. LUCENE-593: Fixed LuceneDictionary's inner Iterator
  (Kåre Fiedler Christiansen via Otis Gospodnetic)
12. LUCENE-641: fixed an off-by-one bug with IndexWriter.setMaxFieldLength()
  (Daniel Naber)
13. LUCENE-659: Make PerFieldAnalyzerWrapper delegate getPositionIncrementGap() to the correct analyzer for the field.
  (Chuck Williams via Yonik Seeley)
14. LUCENE-650: Fixed NPE in Locale specific String Sort when Document has no value.
  (Oliver Hutchison via Chris Hostetter)
15. LUCENE-683: Fixed data corruption when reading lazy loaded fields.
  (Yonik Seeley)
16. LUCENE-678: Fixed bug in NativeFSLockFactory which caused the same lock to be shared between different directories.
  (Michael McCandless via Yonik Seeley)
17. LUCENE-690: Fixed thread unsafe use of IndexInput by lazy loaded fields.
  (Yonik Seeley)
18. LUCENE-696: Fix bug when scorer for DisjunctionMaxQuery has skipTo() called on it before next().
  (Yonik Seeley)
19. LUCENE-569: Fixed SpanNearQuery bug, for 'inOrder' queries it would fail to recognize ordered spans if they overlapped with unordered spans.
  (Paul Elschot via Chris Hostetter)
20. LUCENE-706: Updated fileformats.xml|html concerning the docdelta value in the frequency file.
  (Johan Stuyts, Doron Cohen via Grant Ingersoll)
21. LUCENE-715: Fixed private constructor in IndexWriter.java to properly release the acquired write lock if there is an IOException after acquiring the write lock but before finishing instantiation.
  (Matthew Bogosian via Mike McCandless)
22. LUCENE-651: Multiple different threads requesting the same FieldCache entry (often for Sorting by a field) at the same time caused multiple generations of that entry, which was detrimental to performance and memory use.
  (Oliver Hutchison via Otis Gospodnetic)
23. LUCENE-717: Fixed build.xml not to fail when there is no lib dir.
  (Doron Cohen via Otis Gospodnetic)
24. LUCENE-728: Removed duplicate/old MoreLikeThis and SimilarityQueries classes from contrib/similarity, as their new home is under contrib/queries.
  (Otis Gospodnetic)
25. LUCENE-669: Do not double-close the RandomAccessFile in FSIndexInput/Output during finalize(). Besides sending an IOException up to the GC, this may also be the cause intermittent "The handle is invalid" IOExceptions on Windows when trying to close readers or writers.
  (Michael Busch via Mike McCandless)
26. LUCENE-702: Fix IndexWriter.addIndexes(*) to not corrupt the index on any exceptions (eg disk full). The semantics of these methods is now transactional: either all indices are merged or none are. Also fixed IndexWriter.mergeSegments (called outside of addIndexes(*) by addDocument, optimize, flushRamSegments) and IndexReader.commit() (called by close) to clean up and keep the instance state consistent to what's actually in the index
  (Mike McCandless).
27. LUCENE-129: Change finalizers to do "try {...} finally {super.finalize();}" to make sure we don't miss finalizers in classes above us.
  (Esmond Pitt via Mike McCandless)
28. LUCENE-754: Fix a problem introduced by LUCENE-651, causing IndexReaders to hang around forever, in addition to not fixing the original FieldCache performance problem.
  (Chris Hostetter, Yonik Seeley)
29. LUCENE-140: Fix IndexReader.deleteDocument(int docNum) to correctly raise ArrayIndexOutOfBoundsException when docNum is too large. Previously, if docNum was only slightly too large (within the same multiple of 8, ie, up to 7 ints beyond maxDoc), no exception would be raised and instead the index would become silently corrupted. The corruption then only appears much later, in mergeSegments, when the corrupted segment is merged with segment(s) after it.
  (Mike McCandless)
30. LUCENE-768: Fix case where an Exception during deleteDocument, undeleteAll or setNorm in IndexReader could leave the reader in a state where close() fails to release the write lock.
  (Mike McCandless)
31. Remove "tvp" from known index file extensions because it is never used.
  (Nicolas Lalevée via Bernhard Messer)
32. LUCENE-767: Change how SegmentReader.maxDoc() is computed to not rely on file length check and instead use the SegmentInfo's docCount that's already stored explicitly in the index. This is a defensive bug fix (ie, there is no known problem seen "in real life" due to this, just a possible future problem).
  (Chuck Williams via Mike McCandless)
Optimizations (16)
1. LUCENE-586: TermDocs.skipTo() is now more efficient for multi-segment indexes. This will improve the performance of many types of queries against a non-optimized index.
  (Andrew Hudson via Yonik Seeley)
2. LUCENE-623: RAMDirectory.close now nulls out its reference to all internal "files", allowing them to be GCed even if references to the RAMDirectory itself still exist.
  (Nadav Har'El via Chris Hostetter)
3. LUCENE-629: Compressed fields are no longer uncompressed and recompressed during segment merges (e.g. during indexing or optimizing), thus improving performance .
  (Michael Busch via Otis Gospodnetic)
4. LUCENE-388: Improve indexing performance when maxBufferedDocs is large by keeping a count of buffered documents rather than counting after each document addition.
  (Doron Cohen, Paul Smith, Yonik Seeley)
5. Modified TermScorer.explain to use TermDocs.skipTo() instead of looping through docs.
  (Grant Ingersoll)
6. LUCENE-672: New indexing segment merge policy flushes all buffered docs to their own segment and delays a merge until mergeFactor segments of a certain level have been accumulated. This increases indexing performance in the presence of deleted docs or partially full segments as well as enabling future optimizations.
  NOTE: this also fixes an "under-merging" bug whereby it is possible to get far too many segments in your index (which will drastically slow down search, risks exhausting file descriptor limit, etc.). This can happen when the number of buffered docs at close, plus the number of docs in the last non-ram segment is greater than mergeFactor.
  (Ning Li, Yonik Seeley)
7. Lazy loaded fields unnecessarily retained an extra copy of loaded String data.
  (Yonik Seeley)
8. LUCENE-443: ConjunctionScorer performance increase. Speed up any BooleanQuery with more than one mandatory clause.
  (Abdul Chaudhry, Paul Elschot via Yonik Seeley)
9. LUCENE-365: DisjunctionSumScorer performance increase of ~30%. Speeds up queries with optional clauses.
  (Paul Elschot via Yonik Seeley)
10. LUCENE-695: Optimized BufferedIndexInput.readBytes() for medium size buffers, which will speed up merging and retrieving binary and compressed fields.
  (Nadav Har'El via Yonik Seeley)
11. LUCENE-687: Lazy skipping on proximity file speeds up most queries involving term positions, including phrase queries.
  (Michael Busch via Yonik Seeley)
12. LUCENE-714: Replaced 2 cases of manual for-loop array copying with calls to System.arraycopy instead, in DocumentWriter.java.
  (Nicolas Lalevee via Mike McCandless)
13. LUCENE-729: Non-recursive skipTo and next implementation of TermDocs for a MultiReader. The old implementation could recurse up to the number of segments in the index.
  (Yonik Seeley)
14. LUCENE-739: Improve segment merging performance by reusing the norm array across different fields and doing bulk writes of norms of segments with no deleted docs.
  (Michael Busch via Yonik Seeley)
15. LUCENE-745: Add BooleanQuery.clauses(), allowing direct access to the List of clauses and replaced the internal synchronized Vector with an unsynchronized List.
  (Yonik Seeley)
16. LUCENE-750: Remove finalizers from FSIndexOutput and move the FSIndexInput finalizer to the actual file so all clones don't register a new finalizer.
  (Yonik Seeley)
Test Cases (3)
1. Added TestTermScorer.java
  (Grant Ingersoll)
2. Added TestWindowsMMap.java
  (Benson Margulies via Mike McCandless)
3. LUCENE-744 Append the user.name property onto the temporary directory that is created so it doesn't interfere with other users.
  (Grant Ingersoll)
Documentation (11)
1. Added style sheet to xdocs named lucene.css and included in the Anakia VSL descriptor.
  (Grant Ingersoll)
2. Added scoring.xml document into xdocs. Updated Similarity.java scoring formula.
  (Grant Ingersoll and Steve Rowe. Updates from: Michael McCandless, Doron Cohen, Chris Hostetter, Doug Cutting). Issue 664.
3. Added javadocs for FieldSelectorResult.java.
  (Grant Ingersoll)
4. Moved xdocs directory to src/site/src/documentation/content/xdocs per Issue 707. Site now builds using Forrest, just like the other Lucene siblings. See http://wiki.apache.org/jakarta-lucene/HowToUpdateTheWebsite for info on updating the website.
  (Grant Ingersoll with help from Steve Rowe, Chris Hostetter, Doug Cutting, Otis Gospodnetic, Yonik Seeley)
5. Added in Developer and System Requirements sections under Resources
  (Grant Ingersoll)
6. LUCENE-713 Updated the Term Vector section of File Formats to include documentation on how Offset and Position info are stored in the TVF file.
  (Grant Ingersoll, Samir Abdou)
7. Added in link to Clover Test Code Coverage Reports under the Develop section in Resources
  (Grant Ingersoll)
8. LUCENE-748: Added details for semantics of IndexWriter.close on hitting an Exception.
  (Jed Wesley-Smith via Mike McCandless)
9. Added some text about what is contained in releases.
  (Eric Haszlakiewicz via Grant Ingersoll)
10. LUCENE-758: Fix javadoc to clarify that RAMDirectory(Directory) makes a full copy of the starting Directory.
  (Mike McCandless)
11. LUCENE-764: Fix javadocs to detail temporary space requirements for IndexWriter's optimize(), addIndexes(*) and addDocument(...) methods.
  (Mike McCandless)
Build (3)
1. Added in clover test code coverage per LUCENE-721 To enable clover code coverage, you must have clover.jar in the ANT classpath and specify -Drun.clover=true on the command line.
  (Michael Busch and Grant Ingersoll)
2. Added a sysproperty in common-build.xml per Lucene 752 to map java.io.tmpdir to ${build.dir}/test just like the tempDir sysproperty.
3. LUCENE-757 Added new target named init-dist that does setup for distribution of both binary and source distributions. Called by package and package-*-src

Release 2.0.0

API Changes (4)
1. All deprecated methods and fields have been removed, except DateField, which will still be supported for some time so Lucene can read its date fields from old indexes
  (Yonik Seeley & Grant Ingersoll)
2. DisjunctionSumScorer is no longer public.
  (Paul Elschot via Otis Gospodnetic)
3. Creating a Field with both an empty name and an empty value now throws an IllegalArgumentException
  (Daniel Naber)
4. LUCENE-301: Added new IndexWriter({String,File,Directory}, Analyzer) constructors that do not take a boolean "create" argument. These new constructors will create a new index if necessary, else append to the existing one.
  (Dan Armbrust via Mike McCandless)
New features (2)
1. LUCENE-496: Command line tool for modifying the field norms of an existing index; added to contrib/miscellaneous.
  (Chris Hostetter)
2. LUCENE-577: SweetSpotSimilarity added to contrib/miscellaneous.
  (Chris Hostetter)
Bug fixes (16)
1. LUCENE-330: Fix issue of FilteredQuery not working properly within BooleanQuery.
  (Paul Elschot via Erik Hatcher)
2. LUCENE-515: Make ConstantScoreRangeQuery and ConstantScoreQuery work with RemoteSearchable.
  (Philippe Laflamme via Yonik Seeley)
3. Added methods to get/set writeLockTimeout and commitLockTimeout in IndexWriter. These could be set in Lucene 1.4 using a system property. This feature had been removed without adding the corresponding getter/setter methods.
  (Daniel Naber)
4. LUCENE-413: Fixed ArrayIndexOutOfBoundsException exceptions when using SpanQueries.
  (Paul Elschot via Yonik Seeley)
5. Implemented FilterIndexReader.getVersion() and isCurrent()
  (Yonik Seeley)
6. LUCENE-540: Fixed a bug with IndexWriter.addIndexes(Directory[]) that sometimes caused the index order of documents to change.
  (Yonik Seeley)
7. LUCENE-526: Fixed a bug in FieldSortedHitQueue that caused subsequent String sorts with different locales to sort identically.
  (Paul Cowan via Yonik Seeley)
8. LUCENE-541: Add missing extractTerms() to DisjunctionMaxQuery
  (Stefan Will via Yonik Seeley)
9. LUCENE-514: Added getTermArrays() and extractTerms() to MultiPhraseQuery
  (Eric Jain & Yonik Seeley)
10. LUCENE-512: Fixed ClassCastException in ParallelReader.getTermFreqVectors
  (frederic via Yonik)
11. LUCENE-352: Fixed bug in SpanNotQuery that manifested as NullPointerException when "exclude" query was not a SpanTermQuery.
  (Chris Hostetter)
12. LUCENE-572: Fixed bug in SpanNotQuery hashCode, was ignoring exclude clause
  (Chris Hostetter)
13. LUCENE-561: Fixed some ParallelReader bugs. NullPointerException if the reader didn't know about the field yet, reader didn't keep track if it had deletions, and deleteDocument calls could circumvent synchronization on the subreaders.
  (Chuck Williams via Yonik Seeley)
14. LUCENE-556: Added empty extractTerms() implementation to MatchAllDocsQuery and ConstantScoreQuery in order to allow their use with a MultiSearcher.
  (Yonik Seeley)
15. LUCENE-546: Removed 2GB file size limitations for RAMDirectory.
  (Peter Royal, Michael Chan, Yonik Seeley)
16. LUCENE-485: Don't hold commit lock while removing obsolete index files.
  (Luc Vanlerberghe via cutting)

Release 1.9.1 [2006-03-02]

Bug fixes (1)
1. LUCENE-511: Fix a bug in the BufferedIndexOutput optimization introduced in 1.9-final.
  (Shay Banon & Steven Tamm via cutting)

Release 1.9 final [2006-02-27]

Note that this release is mostly but not 100% source compatible with the previous release of Lucene (1.4.3). In other words, you should make sure your application compiles with this version of Lucene before you replace the old Lucene JAR with the new one. Many methods have been deprecated in anticipation of release 2.0, so deprecation warnings are to be expected when upgrading from 1.4.3 to 1.9.
Bug fixes (1)
1. The fix that made IndexWriter.setMaxBufferedDocs(1) work had negative effects on indexing performance and has thus been reverted. The argument for setMaxBufferedDocs(int) must now at least be 2, otherwise an exception is thrown.
  (Daniel Naber)
Optimizations (1)
1. Optimized BufferedIndexOutput.writeBytes() to use System.arraycopy() in more cases, rather than copying byte-by-byte.
  (Lukas Zapletal via Cutting)

Release 1.9 RC1 [2006-02-21]

Requirements (1)
1. To compile and use Lucene you now need Java 1.4 or later.
Changes in runtime behavior (9)
1. FuzzyQuery can no longer throw a TooManyClauses exception. If a FuzzyQuery expands to more than BooleanQuery.maxClauseCount terms only the BooleanQuery.maxClauseCount most similar terms go into the rewritten query and thus the exception is avoided.
  (Christoph)
2. Changed system property from "org.apache.lucene.lockdir" to "org.apache.lucene.lockDir", so that its casing follows the existing pattern used in other Lucene system properties.
  (Bernhard)
3. The terms of RangeQueries and FuzzyQueries are now converted to lowercase by default (as it has been the case for PrefixQueries and WildcardQueries before). Use setLowercaseExpandedTerms(false) to disable that behavior but note that this also affects PrefixQueries and WildcardQueries.
  (Daniel Naber)
4. Document frequency that is computed when MultiSearcher is used is now computed correctly and "globally" across subsearchers and indices, while before it used to be computed locally to each index, which caused ranking across multiple indices not to be equivalent.
  (Chuck Williams, Wolf Siberski via Otis, bug #31841 [LUCENE-295])
5. When opening an IndexWriter with create=true, Lucene now only deletes its own files from the index directory (looking at the file name suffixes to decide if a file belongs to Lucene). The old behavior was to delete all files.
  (Daniel Naber and Bernhard Messer, bug #34695 [LUCENE-385])
6. The version of an IndexReader, as returned by getCurrentVersion() and getVersion() doesn't start at 0 anymore for new indexes. Instead, it is now initialized by the system time in milliseconds.
  (Bernhard Messer via Daniel Naber)
7. Several default values cannot be set via system properties anymore, as this has been considered inappropriate for a library like Lucene. For most properties there are set/get methods available in IndexWriter which you should use instead. This affects the following properties: See IndexWriter for getter/setter methods: org.apache.lucene.writeLockTimeout, org.apache.lucene.commitLockTimeout, org.apache.lucene.minMergeDocs, org.apache.lucene.maxMergeDocs, org.apache.lucene.maxFieldLength, org.apache.lucene.termIndexInterval, org.apache.lucene.mergeFactor, See BooleanQuery for getter/setter methods: org.apache.lucene.maxClauseCount See FSDirectory for getter/setter methods: disableLuceneLocks
  (Daniel Naber)
8. Fixed FieldCacheImpl to use user-provided IntParser and FloatParser, instead of using Integer and Float classes for parsing.
  (Yonik Seeley via Otis Gospodnetic)
9. Expert level search routines returning TopDocs and TopFieldDocs no longer normalize scores. This also fixes bugs related to MultiSearchers and score sorting/normalization.
  (Luc Vanlerberghe via Yonik Seeley, LUCENE-469)
New features (33)
1. Added support for stored compressed fields (patch #31149 [LUCENE-274])
  (Bernhard Messer via Christoph)
2. Added support for binary stored fields (patch #29370 [LUCENE-229])
  (Drew Farris and Bernhard Messer via Christoph)
3. Added support for position and offset information in term vectors (patch #18927 [LUCENE-95]).
  (Grant Ingersoll & Christoph)
4. A new class DateTools has been added. It allows you to format dates in a readable format adequate for indexing. Unlike the existing DateField class DateTools can cope with dates before 1970 and it forces you to specify the desired date resolution (e.g. month, day, second, ...) which can make RangeQuerys on those fields more efficient.
  (Daniel Naber)
5. QueryParser now correctly works with Analyzers that can return more than one token per position. For example, a query "+fast +car" would be parsed as "+fast +(car automobile)" if the Analyzer returns "car" and "automobile" at the same position whenever it finds "car" (Patch #23307 [LUCENE-133]).
  (Pierrick Brihaye, Daniel Naber)
6. Permit unbuffered Directory implementations (e.g., using mmap). InputStream is replaced by the new classes IndexInput and BufferedIndexInput. OutputStream is replaced by the new classes IndexOutput and BufferedIndexOutput. InputStream and OutputStream are now deprecated and FSDirectory is now subclassable.
  (cutting)
7. Add native Directory and TermDocs implementations that work under GCJ. These require GCC 3.4.0 or later and have only been tested on Linux. Use 'ant gcj' to build demo applications.
  (cutting)
8. Add MMapDirectory, which uses nio to mmap input files. This is still somewhat slower than FSDirectory. However it uses less memory per query term, since a new buffer is not allocated per term, which may help applications which use, e.g., wildcard queries. It may also someday be faster.
  (cutting & Paul Elschot)
9. Added javadocs-internal to build.xml - bug #30360 [LUCENE-250]
  (Paul Elschot via Otis)
10. Added RangeFilter, a more generically useful filter than DateFilter.
  (Chris M Hostetter via Erik)
11. Added NumberTools, a utility class indexing numeric fields.
  (adapted from code contributed by Matt Quail; committed by Erik)
12. Added public static IndexReader.main(String[] args) method. IndexReader can now be used directly at command line level to list and optionally extract the individual files from an existing compound index file.
  (adapted from code contributed by Garrett Rooney; committed by Bernhard)
13. Add IndexWriter.setTermIndexInterval() method. See javadocs.
  (Doug Cutting)
14. Added LucenePackage, whose static get() method returns java.util.Package, which lets the caller get the Lucene version information specified in the Lucene Jar.
  (Doug Cutting via Otis)
15. Added Hits.iterator() method and corresponding HitIterator and Hit objects. This provides standard java.util.Iterator iteration over Hits. Each call to the iterator's next() method returns a Hit object.
  (Jeremy Rayner via Erik)
16. Add ParallelReader, an IndexReader that combines separate indexes over different fields into a single virtual index.
  (Doug Cutting)
17. Add IntParser and FloatParser interfaces to FieldCache, so that fields in arbitrarily formats can be cached as ints and floats.
  (Doug Cutting)
18. Added class org.apache.lucene.index.IndexModifier which combines IndexWriter and IndexReader, so you can add and delete documents without worrying about synchronization/locking issues.
  (Daniel Naber)
19. Lucene can now be used inside an unsigned applet, as Lucene's access to system properties will not cause a SecurityException anymore.
  (Jon Schuster via Daniel Naber, bug #34359 [LUCENE-369])
20. Added a new class MatchAllDocsQuery that matches all documents.
  (John Wang via Daniel Naber, bug #34946 [LUCENE-389])
21. Added ability to omit norms on a per field basis to decrease index size and memory consumption when there are many indexed fields. See Field.setOmitNorms()
  (Yonik Seeley, LUCENE-448)
22. Added NullFragmenter to contrib/highlighter, which is useful for highlighting entire documents or fields.
  (Erik Hatcher)
23. Added regular expression queries, RegexQuery and SpanRegexQuery. Note the same term enumeration caveats apply with these queries as apply to WildcardQuery and other term expanding queries. These two new queries are not currently supported via QueryParser.
  (Erik Hatcher)
24. Added ConstantScoreQuery which wraps a filter and produces a score equal to the query boost for every matching document.
  (Yonik Seeley, LUCENE-383)
25. Added ConstantScoreRangeQuery which produces a constant score for every document in the range. One advantage over a normal RangeQuery is that it doesn't expand to a BooleanQuery and thus doesn't have a maximum number of terms the range can cover. Both endpoints may also be open.
  (Yonik Seeley, LUCENE-383)
26. Added ability to specify a minimum number of optional clauses that must match in a BooleanQuery. See BooleanQuery.setMinimumNumberShouldMatch().
  (Paul Elschot, Chris Hostetter via Yonik Seeley, LUCENE-395)
27. Added DisjunctionMaxQuery which provides the maximum score across its clauses. It's very useful for searching across multiple fields.
  (Chuck Williams via Yonik Seeley, LUCENE-323)
28. New class ISOLatin1AccentFilter that replaces accented characters in the ISO Latin 1 character set by their unaccented equivalent.
  (Sven Duzont via Erik Hatcher)
29. New class KeywordAnalyzer. "Tokenizes" the entire stream as a single token. This is useful for data like zip codes, ids, and some product names.
  (Erik Hatcher)
30. Copied LengthFilter from contrib area to core. Removes words that are too long and too short from the stream.
  (David Spencer via Otis and Daniel)
31. Added getPositionIncrementGap(String fieldName) to Analyzer. This allows custom analyzers to put gaps between Field instances with the same field name, preventing phrase or span queries crossing these boundaries. The default implementation issues a gap of 0, allowing the default token position increment of 1 to put the next field's first token into a successive position.
  (Erik Hatcher, with advice from Yonik)
32. StopFilter can now ignore case when checking for stop words.
  (Grant Ingersoll via Yonik, LUCENE-248)
33. Add TopDocCollector and TopFieldDocCollector. These simplify the implementation of hit collectors that collect only the top-scoring or top-sorting hits.
API Changes (5)
1. Several methods and fields have been deprecated. The API documentation contains information about the recommended replacements. It is planned that most of the deprecated methods and fields will be removed in Lucene 2.0.
  (Daniel Naber)
2. The Russian and the German analyzers have been moved to contrib/analyzers. Also, the WordlistLoader class has been moved one level up in the hierarchy and is now org.apache.lucene.analysis.WordlistLoader
  (Daniel Naber)
3. The API contained methods that declared to throw an IOException but that never did this. These declarations have been removed. If your code tries to catch these exceptions you might need to remove those catch clauses to avoid compile errors.
  (Daniel Naber)
4. Add a serializable Parameter Class to standardize parameter enum classes in BooleanClause and Field.
  (Christoph)
5. Added rewrite methods to all SpanQuery subclasses that nest other SpanQuerys. This allows custom SpanQuery subclasses that rewrite (for term expansion, for example) to nest within the built-in SpanQuery classes successfully.
Bug fixes (24)
1. The JSP demo page (src/jsp/results.jsp) now properly closes the IndexSearcher it opens.
  (Daniel Naber)
2. Fixed a bug in IndexWriter.addIndexes(IndexReader[] readers) that prevented deletion of obsolete segments.
  (Christoph Goller)
3. Fix in FieldInfos to avoid the return of an extra blank field in IndexReader.getFieldNames() (Patch #19058 [LUCENE-102]).
  (Mark Harwood via Bernhard)
4. Some combinations of BooleanQuery and MultiPhraseQuery (formerly PhrasePrefixQuery) could provoke UnsupportedOperationException (bug #33161 [LUCENE-337]).
  (Rhett Sutphin via Daniel Naber)
5. Small bug in skipTo of ConjunctionScorer that caused NullPointerException if skipTo() was called without prior call to next() fixed.
  (Christoph)
6. Disable Similiarty.coord() in the scoring of most automatically generated boolean queries. The coord() score factor is appropriate when clauses are independently specified by a user, but is usually not appropriate when clauses are generated automatically, e.g., by a fuzzy, wildcard or range query. Matches on such automatically generated queries are no longer penalized for not matching all terms.
  (Doug Cutting, Patch #33472 [LUCENE-346])
7. Getting a lock file with Lock.obtain(long) was supposed to wait for a given amount of milliseconds, but this didn't work.
  (John Wang via Daniel Naber, Bug #33799 [LUCENE-353])
8. Fix FSDirectory.createOutput() to always create new files. Previously, existing files were overwritten, and an index could be corrupted when the old version of a file was longer than the new. Now any existing file is first removed.
  (Doug Cutting)
9. Fix BooleanQuery containing nested SpanTermQuery's, which previously could return an incorrect number of hits.
  (Reece Wilton via Erik Hatcher, Bug #35157 [LUCENE-393])
10. Fix NullPointerException that could occur with a MultiPhraseQuery inside a BooleanQuery.
  (Hans Hjelm and Scotty Allen via Daniel Naber, Bug #35626 [LUCENE-404])
11. Fixed SnowballFilter to pass through the position increment from the original token.
  (Yonik Seeley via Erik Hatcher, LUCENE-437)
12. Added Unicode range of Korean characters to StandardTokenizer, grouping contiguous characters into a token rather than one token per character. This change also changes the token type to "<CJ>" for Chinese and Japanese character tokens (previously it was "<CJK>").
  (Cheolgoo Kang via Otis and Erik, LUCENE-444 and LUCENE-461)
13. FieldsReader now looks at FieldInfo.storeOffsetWithTermVector and FieldInfo.storePositionWithTermVector and creates the Field with correct TermVector parameter.
  (Frank Steinmann via Bernhard, LUCENE-455)
14. Fixed WildcardQuery to prevent "cat" matching "ca??".
  (Xiaozheng Ma via Bernhard, LUCENE-306)
15. Fixed a bug where MultiSearcher and ParallelMultiSearcher could change the sort order when sorting by string for documents without a value for the sort field.
  (Luc Vanlerberghe via Yonik, LUCENE-453)
16. Fixed a sorting problem with MultiSearchers that can lead to missing or duplicate docs due to equal docs sorting in an arbitrary order.
  (Yonik Seeley, LUCENE-456)
17. A single hit using the expert level sorted search methods resulted in the score not being normalized.
  (Yonik Seeley, LUCENE-462)
18. Fixed inefficient memory usage when loading an index into RAMDirectory.
  (Volodymyr Bychkoviak via Bernhard, LUCENE-475)
19. Corrected term offsets returned by ChineseTokenizer.
  (Ray Tsang via Erik Hatcher, LUCENE-324)
20. Fixed MultiReader.undeleteAll() to correctly update numDocs.
  (Robert Kirchgessner via Doug Cutting, LUCENE-479)
21. Race condition in IndexReader.getCurrentVersion() and isCurrent() fixed by acquiring the commit lock.
  (Luc Vanlerberghe via Yonik Seeley, LUCENE-481)
22. IndexWriter.setMaxBufferedDocs(1) didn't have the expected effect, this has now been fixed.
  (Daniel Naber)
23. Fixed QueryParser when called with a date in local form like "[1/16/2000 TO 1/18/2000]". This query did not include the documents of 1/18/2000, i.e. the last day was not included.
  (Daniel Naber)
24. Removed sorting constraint that threw an exception if there were not yet any values for the sort field
  (Yonik Seeley, LUCENE-374)
Optimizations (11)
1. Disk usage (peak requirements during indexing and optimization) in case of compound file format has been improved.
  (Bernhard, Dmitry, and Christoph)
2. Optimize the performance of certain uses of BooleanScorer, TermScorer and IndexSearcher. In particular, a BooleanQuery composed of TermQuery, with not all terms required, that returns a TopDocs (e.g., through a Hits with no Sort specified) runs much faster.
  (cutting)
3. Removed synchronization from reading of term vectors with an IndexReader (Patch #30736 [LUCENE-265]).
  (Bernhard Messer via Christoph)
4. Optimize term-dictionary lookup to allocate far fewer terms when scanning for the matching term. This speeds searches involving low-frequency terms, where the cost of dictionary lookup can be significant.
  (cutting)
5. Optimize fuzzy queries so the standard fuzzy queries with a prefix of 0 now run 20-50% faster (Patch #31882 [LUCENE-296]).
  (Jonathan Hager via Daniel Naber)
6. A Version of BooleanScorer (BooleanScorer2) added that delivers documents in increasing order and implements skipTo. For queries with required or forbidden clauses it may be faster than the old BooleanScorer, for BooleanQueries consisting only of optional clauses it is probably slower. The new BooleanScorer is now the default.
  (Patch 31785 [LUCENE-294] by Paul Elschot via Christoph)
7. Use uncached access to norms when merging to reduce RAM usage. (Bug #32847 [LUCENE-326]).
  (Doug Cutting)
8. Don't read term index when random-access is not required. This reduces time to open IndexReaders and they use less memory when random access is not required, e.g., when merging segments. The term index is now read into memory lazily at the first random-access.
  (Doug Cutting)
9. Optimize IndexWriter.addIndexes(Directory[]) when the number of added indexes is larger than mergeFactor. Previously this could result in quadratic performance. Now performance is n log(n).
  (Doug Cutting)
10. Speed up the creation of TermEnum for indices with multiple segments and deleted documents, and thus speed up PrefixQuery, RangeQuery, WildcardQuery, FuzzyQuery, RangeFilter, DateFilter, and sorting the first time on a field.
  (Yonik Seeley, LUCENE-454)
11. Optimized and generalized 32 bit floating point to byte (custom 8 bit floating point) conversions. Increased the speed of Similarity.encodeNorm() anywhere from 10% to 250%, depending on the JVM.
  (Yonik Seeley, LUCENE-467)
Infrastructure (2)
1. Lucene's source code repository has converted from CVS to Subversion. The new repository is at http://svn.apache.org/repos/asf/lucene/java/trunk
2. Lucene's issue tracker has migrated from Bugzilla to JIRA. Lucene's JIRA is at http://issues.apache.org/jira/browse/LUCENE The old issues are still available at http://issues.apache.org/bugzilla/show_bug.cgi?id=xxxx (use the bug number instead of xxxx)

Release 1.4.3 [2004-12-07]

The JSP demo page (src/jsp/results.jsp) now properly escapes error messages which might contain user input (e.g. error messages about query parsing). If you used that page as a starting point for your own code please make sure your code also properly escapes HTML characters from user input in order to avoid so-called cross site scripting attacks.
(Daniel Naber)
QueryParser changes in 1.4.2 broke the QueryParser API. Now the old API is supported again.
(Christoph)

Release 1.4.2 [2004-10-01]

Fixed bug #31241 [LUCENE-277]: Sorting could lead to incorrect results (documents missing, others duplicated) if the sort keys were not unique and there were more than 100 matches.
(Daniel Naber)
Memory leak in Sort code (bug #31240 [LUCENE-276]) eliminated.
(Rafal Krzewski via Christoph and Daniel)
FuzzyQuery now takes an additional parameter that specifies the minimum similarity that is required for a term to match the query. The QueryParser syntax for this is term~x, where x is a floating point number >= 0 and < 1 (a bigger number means that a higher similarity is required). Furthermore, a prefix can be specified for FuzzyQuerys so that only those terms are considered similar that start with this prefix. This can speed up FuzzyQuery greatly.
(Daniel Naber, Christoph Goller)
PhraseQuery and PhrasePrefixQuery now allow the explicit specification of relative positions.
(Christoph Goller)
QueryParser changes: Fix for ArrayIndexOutOfBoundsExceptions (patch #9110 [LUCENE-35]); some unused method parameters removed; The ability to specify a minimum similarity for FuzzyQuery has been added.
(Christoph Goller)
IndexSearcher optimization: a new ScoreDoc is no longer allocated for every non-zero-scoring hit. This makes 'OR' queries that contain common terms substantially faster.
(cutting)

Release 1.4.1 [2004-08-02]

Fixed a performance bug in hit sorting code, where values were not correctly cached.
(Aviran via cutting)
Fixed errors in file format documentation.
(Daniel Naber)

Release 1.4 final [2004-07-01]

Added "an" to the list of stop words in StopAnalyzer, to complement the existing "a" there. Fix for bug 28960 [LUCENE-132] (http://issues.apache.org/bugzilla/show_bug.cgi?id=28960).
(Otis)
Added new class FieldCache to manage in-memory caches of field term values.
(Tim Jones)
Added overloaded getFieldQuery method to QueryParser which accepts the slop factor specified for the phrase (or the default phrase slop for the QueryParser instance). This allows overriding methods to replace a PhraseQuery with a SpanNearQuery instead, keeping the proper slop factor.
(Erik Hatcher)
Changed the encoding of GermanAnalyzer.java and GermanStemmer.java to UTF-8 and changed the build encoding to UTF-8, to make changed files compile.
(Otis Gospodnetic)
Removed synchronization from term lookup under IndexReader methods termFreq(), termDocs() or termPositions() to improve multi-threaded performance.
(cutting)
Fix a bug where obsolete segment files were not deleted on Win32.

Release 1.4 RC3 [2004-05-11]

Fixed several search bugs introduced by the skipTo() changes in release 1.4RC1. The index file format was changed a bit, so collections must be re-indexed to take advantage of the skipTo() optimizations.
(Christoph Goller)
Added new Document methods, removeField() and removeFields().
(Christoph Goller)
Fixed inconsistencies with index closing. Indexes and directories are now only closed automatically by Lucene when Lucene opened them automatically.
(Christoph Goller)
Added new class: FilteredQuery.
(Tim Jones)
Added a new SortField type for custom comparators.
(Tim Jones)
Lock obtain timed out message now displays the full path to the lock file.
(Daniel Naber via Erik)
Fixed a bug in SpanNearQuery when ordered.
(Paul Elschot via cutting)
Fixed so that FSDirectory's locks still work when the java.io.tmpdir system property is null.
(cutting)
Changed FilteredTermEnum's constructor to take no parameters, as the parameters were ignored anyway
(bug #28858 [LUCENE-224])

Release 1.4 RC2 [2004-03-30]

GermanAnalyzer now throws an exception if the stopword file cannot be found (bug #27987 [LUCENE-203]). It now uses LowerCaseFilter (bug #18410 [LUCENE-87])
(Daniel Naber via Otis, Erik)
Fixed a few bugs in the file format documentation.
(cutting)

Release 1.4 RC1 [2004-03-29]

Changed the format of the .tis file, so that:
- it has a format version number, which makes it easier to back-compatibly change file formats in the future.
- the term count is now stored as a long. This was the one aspect of the Lucene's file formats which limited index size.
- a few internal index parameters are now stored in the index, so that they can (in theory) now be changed from index to index, although there is not yet an API to do so.
These changes are back compatible. The new code can read old indexes. But old code will not be able read new indexes.
(cutting)
Added an optimized implementation of TermDocs.skipTo(). A skip table is now stored for each term in the .frq file. This only adds a percent or two to overall index size, but can substantially speedup many searches.
(cutting)
Restructured the Scorer API and all Scorer implementations to take advantage of an optimized TermDocs.skipTo() implementation. In particular, PhraseQuerys and conjunctive BooleanQuerys are faster when one clause has substantially fewer matches than the others. (A conjunctive BooleanQuery is a BooleanQuery where all clauses are required.)
(cutting)
Added new class ParallelMultiSearcher. Combined with RemoteSearchable this makes it easy to implement distributed search systems.
(Jean-Francois Halleux via cutting)
Added support for hit sorting. Results may now be sorted by any indexed field. For details see the javadoc for Searcher#search(Query, Sort).
(Tim Jones via Cutting)
Changed FSDirectory to auto-create a full directory tree that it needs by using mkdirs() instead of mkdir().
(Mladen Turk via Otis)
Added a new span-based query API. This implements, among other things, nested phrases. See javadocs for details.
(Doug Cutting)
Added new method Query.getSimilarity(Searcher), and changed scorers to use it. This permits one to subclass a Query class so that it can specify its own Similarity implementation, perhaps one that delegates through that of the Searcher.
(Julien Nioche via Cutting)
Added MultiReader, an IndexReader that combines multiple other IndexReaders.
(Cutting)
Added support for term vectors. See Field#isTermVectorStored().
(Grant Ingersoll, Cutting & Dmitry)
Fixed the old bug with escaping of special characters in query strings: http://issues.apache.org/bugzilla/show_bug.cgi?id=24665
(Jean-Francois Halleux via Otis)
Added support for overriding default values for the following, using system properties:
- default commit lock timeout
- default maxFieldLength
- default maxMergeDocs
- default mergeFactor
- default minMergeDocs
- default write lock timeout
(Otis)
Changed QueryParser.jj to allow '-' and '+' within tokens: http://issues.apache.org/bugzilla/show_bug.cgi?id=27491
(Morus Walter via Otis)
Changed so that the compound index format is used by default. This makes indexing a bit slower, but vastly reduces the chances of file handle problems.
(Cutting)

Release 1.3 final [2003-12-26]

Added catch of BooleanQuery$TooManyClauses in QueryParser to throw ParseException instead.
(Erik Hatcher)
Fixed a NullPointerException in Query.explain().
(Doug Cutting)
Added a new method IndexReader.setNorm(), that permits one to alter the boosting of fields after an index is created.
Distinguish between the final position and length when indexing a field. The length is now defined as the total number of tokens, instead of the final position, as it was previously. Length is used for score normalization (Similarity.lengthNorm()) and for controlling memory usage (IndexWriter.maxFieldLength). In both of these cases, the total number of tokens is a better value to use than the final token position. Position is used in phrase searching (see PhraseQuery and Token.setPositionIncrement()).
Fix StandardTokenizer's handling of CJK characters (Chinese, Japanese and Korean ideograms). Previously contiguous sequences were combined in a single token, which is not very useful. Now each ideogram generates a separate token, which is more useful.

Release 1.3 RC3 [2003-11-25]

Added minMergeDocs in IndexWriter. This can be raised to speed indexing without altering the number of files, but only using more memory.
(Julien Nioche via Otis)
Fix bug #24786 [LUCENE-162], in query rewriting.
(bschneeman via Cutting)
Fix bug #16952 [LUCENE-85], in demo HTML parser, skip comments in javascript.
(Christoph Goller)
Fix bug #19253 [LUCENE-105], in demo HTML parser, add whitespace as needed to output
(Daniel Naber via Christoph Goller)
Fix bug #24301 [LUCENE-159], in demo HTML parser, long titles no longer hang things.
(Christoph Goller)
Fix bug #23534 [LUCENE-138], Replace use of file timestamp of segments file with an index version number stored in the segments file. This resolves problems when running on file systems with low-resolution timestamps, e.g., HFS under MacOS X.
(Christoph Goller)
Fix QueryParser so that TokenMgrError is not thrown, only ParseException.
(Erik Hatcher)
Fix some bugs introduced by change 11 of RC2.
(Christoph Goller)
Fixed a problem compiling TestRussianStem.
(Christoph Goller)
Cleaned up some build stuff.
(Erik Hatcher)

Release 1.3 RC2 [2003-10-22]

Added getFieldNames(boolean) to IndexReader, SegmentReader, and SegmentsReader.
(Julien Nioche via otis)
Changed file locking to place lock files in System.getProperty("java.io.tmpdir"), where all users are permitted to write files. This way folks can open and correctly lock indexes which are read-only to them.
IndexWriter: added a new method, addDocument(Document, Analyzer), permitting one to easily use different analyzers for different documents in the same index.
Minor enhancements to FuzzyTermEnum.
(Christoph Goller via Otis)
PriorityQueue: added insert(Object) method and adjusted IndexSearcher and MultiIndexSearcher to use it.
(Christoph Goller via Otis)
Fixed a bug in IndexWriter that returned incorrect docCount().
(Christoph Goller via Otis)
Fixed SegmentsReader to eliminate the confusing and slightly different behaviour of TermEnum when dealing with an enumeration of all terms, versus an enumeration starting from a specific term. This patch also fixes incorrect term document frequencies when the same term is present in multiple segments.
(Christoph Goller via Otis)
Added CachingWrapperFilter and PerFieldAnalyzerWrapper.
(Erik Hatcher)
Added support for the new "compound file" index format
(Dmitry Serebrennikov)
Added Locale setting to QueryParser, for use by date range parsing.
Changed IndexReader so that it can be subclassed by classes outside of its package. Previously it had package-private abstract methods. Also modified the index merging code so that it can work on an arbitrary IndexReader implementation, and added a new method, IndexWriter.addIndexes(IndexReader[]), to take advantage of this.
(cutting)
Added a limit to the number of clauses which may be added to a BooleanQuery. The default limit is 1024 clauses. This should stop most OutOfMemoryExceptions by prefix, wildcard and fuzzy queries which run amok.
(cutting)
Add new method: IndexReader.undeleteAll(). This undeletes all deleted documents which still remain in the index.
(cutting)

Release 1.3 RC1 [2003-03-24]

Fixed PriorityQueue's clear() method. Fix for bug 9454 [LUCENE-37], http://nagoya.apache.org/bugzilla/show_bug.cgi?id=9454
(Matthijs Bomhoff via otis)
Changed StandardTokenizer.jj grammar for EMAIL tokens. Fix for bug 9015 [LUCENE-34], http://nagoya.apache.org/bugzilla/show_bug.cgi?id=9015
(Dale Anson via otis)
Added the ability to disable lock creation by using disableLuceneLocks system property. This is useful for read-only media, such as CD-ROMs.
(otis)
Added id method to Hits to be able to access the index global id. Required for sorting options.
(carlson)
Added support for new range query syntax to QueryParser.jj.
(briangoetz)
Added the ability to retrieve HTML documents' META tag values to HTMLParser.jj.
(Mark Harwood via otis)
Modified QueryParser to make it possible to programmatically specify the default Boolean operator (OR or AND).
(Péter Halácsy via otis)
Made many search methods and classes non-final, per requests. This includes IndexWriter and IndexSearcher, among others.
(cutting)
Added class RemoteSearchable, providing support for remote searching via RMI. The test class RemoteSearchableTest.java provides an example of how this can be used.
(cutting)
Added PhrasePrefixQuery (and supporting MultipleTermPositions). The test class TestPhrasePrefixQuery provides the usage example.
(Anders Nielsen via otis)
Changed the German stemming algorithm to ignore case while stripping. The new algorithm is faster and produces more equal stems from nouns and verbs derived from the same word.
(gschwarz)
Added support for boosting the score of documents and fields via the new methods Document.setBoost(float) and Field.setBoost(float).
Note: This changes the encoding of an indexed value. Indexes should be re-created from scratch in order for search scores to be correct. With the new code and an old index, searches will yield very large scores for shorter fields, and very small scores for longer fields. Once the index is re-created, scores will be as before.
(cutting)
Added new method Token.setPositionIncrement().
This permits, for the purpose of phrase searching, placing multiple terms in a single position. This is useful with stemmers that produce multiple possible stems for a word.
This also permits the introduction of gaps between terms, so that terms which are adjacent in a token stream will not be matched by and exact phrase query. This makes it possible, e.g., to build an analyzer where phrases are not matched over stop words which have been removed.
Finally, repeating a token with an increment of zero can also be used to boost scores of matches on that token.
(cutting)
Added new Filter class, QueryFilter. This constrains search results to only match those which also match a provided query. Results are cached, so that searches after the first on the same index using this filter are very fast.
This could be used, for example, with a RangeQuery on a formatted date field to implement date filtering. One could re-use a single QueryFilter that matches, e.g., only documents modified within the last week. The QueryFilter and RangeQuery would only need to be reconstructed once per day.
(cutting)
Added a new IndexWriter method, getAnalyzer(). This returns the analyzer used when adding documents to this index.
(cutting)
Fixed a bug with IndexReader.lastModified(). Before, document deletion did not update this. Now it does.
(cutting)
Added Russian Analyzer.
(Boris Okner via otis)
Added a public, extensible scoring API. For details, see the javadoc for org.apache.lucene.search.Similarity.
Fixed return of Hits.id() from float to int.
(Terry Steichen via Peter).
Added getFieldNames() to IndexReader and Segment(s)Reader classes.
(Peter Mularien via otis)
Added getFields(String) and getValues(String) methods. Contributed by Rasik Pandey on 2002-10-09
(Rasik Pandey via otis)
Revised internal search APIs. Changes include:
a. Queries are no longer modified during a search. This makes it possible, e.g., to reuse the same query instance with multiple indexes from multiple threads.
b. Term-expanding queries (e.g. PrefixQuery, WildcardQuery, etc.) now work correctly with MultiSearcher, fixing bugs 12619 [LUCENE-56] and 12667 [LUCENE-57].
c. Boosting BooleanQuery's now works, and is supported by the query parser (problem reported by Lee Mallabone). Thus a query like "(+foo +bar)^2 +baz" is now supported and equivalent to "(+foo^2 +bar^2) +baz".
d. New method: Query.rewrite(IndexReader). This permits a query to re-write itself as an alternate, more primitive query. Most of the term-expanding query classes (PrefixQuery, WildcardQuery, etc.) are now implemented using this method.
e. New method: Searchable.explain(Query q, int doc). This returns an Explanation instance that describes how a particular document is scored against a query. An explanation can be displayed as either plain text, with the toString() method, or as HTML, with the toHtml() method. Note that computing an explanation is as expensive as executing the query over the entire index. This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit.
f. Scorer and Weight are public, not package protected. It now possible for someone to write a Scorer implementation that is not in the org.apache.lucene.search package. This is still fairly advanced programming, and I don't expect anyone to do this anytime soon, but at least now it is possible.
g. Added public accessors to the primitive query classes (TermQuery, PhraseQuery and BooleanQuery), permitting access to their terms and clauses.
Caution: These are extensive changes and they have not yet been tested extensively. Bug reports are appreciated.
(cutting)
Added convenience RAMDirectory constructors taking File and String arguments, for easy FSDirectory to RAMDirectory conversion.
(otis)
Added code for manual renaming of files in FSDirectory, since it has been reported that java.io.File's renameTo(File) method sometimes fails on Windows JVMs.
(Matt Tucker via otis)
Refactored QueryParser to make it easier for people to extend it. Added the ability to automatically lower-case Wildcard terms in the QueryParser.
(Tatu Saloranta via otis)

Release 1.2 RC6 [2002-06-13]

Changed QueryParser.jj to have "?" be a special character which allowed it to be used as a wildcard term. Updated TestWildcard unit test also.
(Ralf Hettesheimer via carlson)

Release 1.2 RC5 [2002-05-14]

Renamed build.properties to default.properties and updated the BUILD.txt document to describe how to override the default.property settings without having to edit the file. This brings the build process closer to Scarab's build process.
(jon)
Added MultiFieldQueryParser class.
(Kelvin Tan, via otis)
Updated "powered by" links.
(otis)
Fixed instruction for setting up JavaCC - Bug #7017 [LUCENE-18]
(otis)
Added throwing exception if FSDirectory could not create directory
- Bug #6914 [LUCENE-16]
  (Eugene Gluzberg via otis)
Update MultiSearcher, MultiFieldParse, Constants, DateFilter, LowerCaseTokenizer javadoc
(otis)
Added fix to avoid NullPointerException in results.jsp
(Mark Hayes via otis)
Changed Wildcard search to find 0 or more char instead of 1 or more
(Lee Mallobone, via otis)
Fixed error in offset issue in GermanStemFilter - Bug #7412 [LUCENE-23]
(Rodrigo Reyes, via otis)
Added unit tests for wildcard search and DateFilter
(otis)
Allow co-existence of indexed and non-indexed fields with the same name
(cutting/casper, via otis)
Add escape character to query parser.
(briangoetz)
Applied a patch that ensures that searches that use DateFilter don't throw an exception when no matches are found.
(David Smiley, via otis)
Fixed bugs in DateFilter and wildcardquery unit tests.
(cutting, otis, carlson)

Release 1.2 RC4 [2002-02-14]

Updated contributions section of website. Add XML Document #3 implementation to Document Section. Also added Term Highlighting to Misc Section.
(carlson)
Fixed NullPointerException for phrase searches containing unindexed terms, introduced in 1.2RC3.
(cutting)
Changed document deletion code to obtain the index write lock, enforcing the fact that document addition and deletion cannot be performed concurrently.
(cutting)
Various documentation cleanups.
(otis, acoliver)
Updated "powered by" links.
(cutting, jon)
Fixed a bug in the GermanStemmer.
(Bernhard Messer, via otis)
Changed Term and Query to implement Serializable.
(scottganyo)
Fixed to never delete indexes added with IndexWriter.addIndexes().
(cutting)
Upgraded to JUnit 3.7.
(otis)

Release 1.2 RC3 [2002-01-27]

IndexWriter: fixed a bug where adding an optimized index to an empty index failed. This was encountered using addIndexes to copy a RAMDirectory index to an FSDirectory.
RAMDirectory: fixed a bug where RAMInputStream could not read across more than across a single buffer boundary.
Fix query parser so it accepts queries with unicode characters.
(briangoetz)
Fix query parser so that PrefixQuery is used in preference to WildcardQuery when there's only an asterisk at the end of the term. Previously PrefixQuery would never be used.
Fix tests so they compile; fix ant file so it compiles tests properly. Added test cases for Analyzers and PriorityQueue.
Updated demos, added Getting Started documentation.
(acoliver)
Added 'contributions' section to website & docs.
(carlson)
Removed JavaCC from source distribution for copyright reasons. Folks must now download this separately from metamata in order to compile Lucene.
(cutting)
Substantially improved the performance of DateFilter by adding the ability to reuse TermDocs objects.
(cutting)
Added IndexReader methods: public static boolean indexExists(String directory); public static boolean indexExists(File directory); public static boolean indexExists(Directory directory); public static boolean isLocked(Directory directory); public static void unlock(Directory directory);
(cutting, otis)
Fixed bugs in GermanAnalyzer
(gschwarz)

Release 1.2 RC2 [2001-10-19]

added sources to distribution
removed broken build scripts and libraries from distribution
SegmentsReader: fixed potential race condition
FSDirectory: fixed so that getDirectory(xxx,true) correctly erases the directory contents, even when the directory has already been accessed in this JVM.
RangeQuery: Fix issue where an inclusive range query would include the nearest term in the index above a non-existant specified upper term.
SegmentTermEnum: Fix NullPointerException in clone() method when the Term is null.
JDK 1.1 compatibility fix: disabled lock files for JDK 1.1, since they rely on a feature added in JDK 1.2.

Release 1.2 RC1 [2001-10-02]

first Apache release
packages renamed from com.lucene to org.apache.lucene
license switched from LGPL to Apache
ant-only build -- no more makefiles
addition of lock files--now fully thread & process safe
addition of German stemmer
MultiSearcher now supports low-level search API
added RangeQuery, for term-range searching
Analyzers can choose tokenizer based on field name
misc bug fixes.

Release 1.01b [2001-06-02]

last Sourceforge release
a few bug fixes
new Query Parser
new prefix query (search for "foo*" matches "food")

Release 1.0 [2000-10-04]

This release fixes a few serious bugs and also includes some performance optimizations, a stemmer, and a few other minor enhancements.

Release 0.04 [2000-04-19]

Lucene now includes a grammar-based tokenizer, StandardTokenizer.
The only tokenizer included in the previous release (LetterTokenizer) identified terms consisting entirely of alphabetic characters. The new tokenizer uses a regular-expression grammar to identify more complex classes of terms, including numbers, acronyms, email addresses, etc.
StandardTokenizer serves two purposes:
1. It is a much better, general purpose tokenizer for use by applications as is.
The easiest way for applications to start using StandardTokenizer is to use StandardAnalyzer.
2. It provides a good example of grammar-based tokenization.
If an application has special tokenization requirements, it can implement a custom tokenizer by copying the directory containing the new tokenizer into the application and modifying it accordingly.

Release 0.01 [2000-03-30]

First open source release.
The code has been re-organized into a new package and directory structure for this release. It builds OK, but has not been tested beyond that since the re-organization.