Class Lucene40BlockTreeTermsReader
java.lang.Object
org.apache.lucene.index.Fields
org.apache.lucene.codecs.FieldsProducer
org.apache.lucene.backward_codecs.lucene40.blocktree.Lucene40BlockTreeTermsReader
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Iterable<String>
A block-based terms index and dictionary that assigns terms to variable length blocks according
to how they share prefixes. The terms index is a prefix trie whose leaves are term blocks. The
advantage of this approach is that seekExact is often able to determine a term cannot exist
without doing any IO, and intersection with Automata is very fast. Note that this terms
dictionary has its own fixed terms index (ie, it does not support a pluggable terms index
implementation).
NOTE: this terms dictionary supports min/maxItemsPerBlock during indexing to control how much memory the terms index uses.
The data structure used by this implementation is very similar to a burst trie (http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.18.3499), but with added logic to break up too-large blocks of all terms sharing a given prefix into smaller ones.
Use CheckIndex
with the -verbose
option to see
summary statistics on the blocks in the dictionary.
See BlockTreeTermsWriter
.
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Field Summary
Modifier and TypeFieldDescriptionstatic final int
Suffixes are compressed to save space.static final int
Current terms format.static final int
Metadata is written to its own file.static final int
The long[] + byte[] metadata has been replaced with a single byte[].static final int
Initial terms format.Fields inherited from class org.apache.lucene.index.Fields
EMPTY_ARRAY
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Constructor Summary
ConstructorDescriptionLucene40BlockTreeTermsReader
(PostingsReaderBase postingsReader, SegmentReadState state) Sole constructor. -
Method Summary
Methods inherited from class org.apache.lucene.codecs.FieldsProducer
getMergeInstance
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.lang.Iterable
forEach, spliterator
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Field Details
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VERSION_START
public static final int VERSION_STARTInitial terms format.- See Also:
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VERSION_META_LONGS_REMOVED
public static final int VERSION_META_LONGS_REMOVEDThe long[] + byte[] metadata has been replaced with a single byte[].- See Also:
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VERSION_COMPRESSED_SUFFIXES
public static final int VERSION_COMPRESSED_SUFFIXESSuffixes are compressed to save space.- See Also:
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VERSION_META_FILE
public static final int VERSION_META_FILEMetadata is written to its own file.- See Also:
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VERSION_CURRENT
public static final int VERSION_CURRENTCurrent terms format.- See Also:
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Constructor Details
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Lucene40BlockTreeTermsReader
public Lucene40BlockTreeTermsReader(PostingsReaderBase postingsReader, SegmentReadState state) throws IOException Sole constructor.- Throws:
IOException
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Method Details
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close
- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in classFieldsProducer
- Throws:
IOException
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iterator
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terms
- Specified by:
terms
in classFields
- Throws:
IOException
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size
public int size() -
checkIntegrity
- Specified by:
checkIntegrity
in classFieldsProducer
- Throws:
IOException
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toString
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