public class IndexWriter extends Object implements Closeable, TwoPhaseCommit
IndexWriter
creates and maintains an index.
The IndexWriterConfig.OpenMode
option on
IndexWriterConfig.setOpenMode(OpenMode)
determines
whether a new index is created, or whether an existing index is
opened. Note that you can open an index with IndexWriterConfig.OpenMode.CREATE
even while readers are using the index. The old readers will
continue to search the "point in time" snapshot they had opened,
and won't see the newly created index until they re-open. If
IndexWriterConfig.OpenMode.CREATE_OR_APPEND
is used IndexWriter will create a
new index if there is not already an index at the provided path
and otherwise open the existing index.
In either case, documents are added with addDocument
and removed with deleteDocuments(Term)
or deleteDocuments(Query)
. A document can be updated with updateDocument
(which just deletes
and then adds the entire document). When finished adding, deleting
and updating documents, close
should be called.
These changes are buffered in memory and periodically
flushed to the Directory
(during the above method
calls). A flush is triggered when there are enough added documents
since the last flush. Flushing is triggered either by RAM usage of the
documents (see IndexWriterConfig.setRAMBufferSizeMB(double)
) or the
number of added documents (see IndexWriterConfig.setMaxBufferedDocs(int)
).
The default is to flush when RAM usage hits
IndexWriterConfig.DEFAULT_RAM_BUFFER_SIZE_MB
MB. For
best indexing speed you should flush by RAM usage with a
large RAM buffer. Additionally, if IndexWriter reaches the configured number of
buffered deletes (see IndexWriterConfig.setMaxBufferedDeleteTerms(int)
)
the deleted terms and queries are flushed and applied to existing segments.
In contrast to the other flush options IndexWriterConfig.setRAMBufferSizeMB(double)
and
IndexWriterConfig.setMaxBufferedDocs(int)
, deleted terms
won't trigger a segment flush. Note that flushing just moves the
internal buffered state in IndexWriter into the index, but
these changes are not visible to IndexReader until either
commit()
or close()
is called. A flush may
also trigger one or more segment merges which by default
run with a background thread so as not to block the
addDocument calls (see below
for changing the MergeScheduler
).
Opening an IndexWriter
creates a lock file for the directory in use. Trying to open
another IndexWriter
on the same directory will lead to a
LockObtainFailedException
. The LockObtainFailedException
is also thrown if an IndexReader on the same directory is used to delete documents
from the index.
Expert: IndexWriter
allows an optional
IndexDeletionPolicy
implementation to be
specified. You can use this to control when prior commits
are deleted from the index. The default policy is KeepOnlyLastCommitDeletionPolicy
which removes all prior
commits as soon as a new commit is done (this matches
behavior before 2.2). Creating your own policy can allow
you to explicitly keep previous "point in time" commits
alive in the index for some time, to allow readers to
refresh to the new commit without having the old commit
deleted out from under them. This is necessary on
filesystems like NFS that do not support "delete on last
close" semantics, which Lucene's "point in time" search
normally relies on.
Expert:
IndexWriter
allows you to separately change
the MergePolicy
and the MergeScheduler
.
The MergePolicy
is invoked whenever there are
changes to the segments in the index. Its role is to
select which merges to do, if any, and return a MergePolicy.MergeSpecification
describing the merges.
The default is LogByteSizeMergePolicy
. Then, the MergeScheduler
is invoked with the requested merges and
it decides when and how to run the merges. The default is
ConcurrentMergeScheduler
.
NOTE: if you hit an
OutOfMemoryError then IndexWriter will quietly record this
fact and block all future segment commits. This is a
defensive measure in case any internal state (buffered
documents and deletions) were corrupted. Any subsequent
calls to commit()
will throw an
IllegalStateException. The only course of action is to
call close()
, which internally will call rollback()
, to undo any changes to the index since the
last commit. You can also just call rollback()
directly.
NOTE: IndexWriter
instances are completely thread
safe, meaning multiple threads can call any of its
methods, concurrently. If your application requires
external synchronization, you should not
synchronize on the IndexWriter
instance as
this may cause deadlock; use your own (non-Lucene) objects
instead.
NOTE: If you call
Thread.interrupt()
on a thread that's within
IndexWriter, IndexWriter will try to catch this (eg, if
it's in a wait() or Thread.sleep()), and will then throw
the unchecked exception ThreadInterruptedException
and clear the interrupt status on the thread.
Modifier and Type | Class and Description |
---|---|
static class |
IndexWriter.IndexReaderWarmer
If
DirectoryReader.open(IndexWriter,boolean) has
been called (ie, this writer is in near real-time
mode), then after a merge completes, this class can be
invoked to warm the reader on the newly merged
segment, before the merge commits. |
Modifier and Type | Field and Description |
---|---|
static int |
MAX_TERM_LENGTH
Absolute hard maximum length for a term, in bytes once
encoded as UTF8.
|
static String |
SOURCE
Key for the source of a segment in the
diagnostics . |
static String |
SOURCE_ADDINDEXES_READERS
Source of a segment which results from a call to
addIndexes(IndexReader...) . |
static String |
SOURCE_FLUSH
Source of a segment which results from a flush.
|
static String |
SOURCE_MERGE
Source of a segment which results from a merge of other segments.
|
static String |
WRITE_LOCK_NAME
Name of the write lock in the index.
|
Constructor and Description |
---|
IndexWriter(Directory d,
IndexWriterConfig conf)
Constructs a new IndexWriter per the settings given in
conf . |
Modifier and Type | Method and Description |
---|---|
void |
addDocument(Iterable<? extends IndexableField> doc)
Adds a document to this index.
|
void |
addDocument(Iterable<? extends IndexableField> doc,
Analyzer analyzer)
Adds a document to this index, using the provided analyzer instead of the
value of
getAnalyzer() . |
void |
addDocuments(Iterable<? extends Iterable<? extends IndexableField>> docs)
Atomically adds a block of documents with sequentially
assigned document IDs, such that an external reader
will see all or none of the documents.
|
void |
addDocuments(Iterable<? extends Iterable<? extends IndexableField>> docs,
Analyzer analyzer)
Atomically adds a block of documents, analyzed using the
provided analyzer, with sequentially assigned document
IDs, such that an external reader will see all or none
of the documents.
|
void |
addIndexes(Directory... dirs)
Adds all segments from an array of indexes into this index.
|
void |
addIndexes(IndexReader... readers)
Merges the provided indexes into this index.
|
void |
close()
Commits all changes to an index, waits for pending merges
to complete, and closes all associated files.
|
void |
close(boolean waitForMerges)
Closes the index with or without waiting for currently
running merges to finish.
|
void |
commit()
Commits all pending changes (added & deleted
documents, segment merges, added
indexes, etc.) to the index, and syncs all referenced
index files, such that a reader will see the changes
and the index updates will survive an OS or machine
crash or power loss.
|
void |
deleteAll()
Delete all documents in the index.
|
void |
deleteDocuments(Query... queries)
Deletes the document(s) matching any of the provided queries.
|
void |
deleteDocuments(Query query)
Deletes the document(s) matching the provided query.
|
void |
deleteDocuments(Term... terms)
Deletes the document(s) containing any of the
terms.
|
void |
deleteDocuments(Term term)
Deletes the document(s) containing
term . |
void |
deleteUnusedFiles()
Expert: remove any index files that are no longer
used.
|
protected void |
doAfterFlush()
A hook for extending classes to execute operations after pending added and
deleted documents have been flushed to the Directory but before the change
is committed (new segments_N file written).
|
protected void |
doBeforeFlush()
A hook for extending classes to execute operations before pending added and
deleted documents are flushed to the Directory.
|
protected void |
ensureOpen()
Used internally to throw an
AlreadyClosedException if this IndexWriter has been
closed (closed=true ) or is in the process of
closing (closing=true ). |
protected void |
ensureOpen(boolean failIfClosing)
Used internally to throw an
AlreadyClosedException if this
IndexWriter has been closed or is in the process of closing. |
protected void |
flush(boolean triggerMerge,
boolean applyAllDeletes)
Flush all in-memory buffered updates (adds and deletes)
to the Directory.
|
void |
forceMerge(int maxNumSegments)
Forces merge policy to merge segments until there are <=
maxNumSegments.
|
void |
forceMerge(int maxNumSegments,
boolean doWait)
Just like
forceMerge(int) , except you can
specify whether the call should block until
all merging completes. |
void |
forceMergeDeletes()
Forces merging of all segments that have deleted
documents.
|
void |
forceMergeDeletes(boolean doWait)
Just like
forceMergeDeletes() , except you can
specify whether the call should block until the
operation completes. |
Analyzer |
getAnalyzer()
Returns the analyzer used by this index.
|
Map<String,String> |
getCommitData()
Returns the commit user data map that was last committed, or the one that
was set on
setCommitData(Map) . |
LiveIndexWriterConfig |
getConfig()
Returns a
LiveIndexWriterConfig , which can be used to query the IndexWriter
current settings, as well as modify "live" ones. |
Directory |
getDirectory()
Returns the Directory used by this index.
|
Collection<SegmentCommitInfo> |
getMergingSegments()
Expert: to be used by a
MergePolicy to avoid
selecting merges for segments already being merged. |
MergePolicy.OneMerge |
getNextMerge()
Expert: the
MergeScheduler calls this method to retrieve the next
merge requested by the MergePolicy |
boolean |
hasDeletions()
Returns true if this index has deletions (including
buffered deletions).
|
boolean |
hasPendingMerges()
Expert: returns true if there are merges waiting to be scheduled.
|
boolean |
hasUncommittedChanges()
Returns true if there may be changes that have not been
committed.
|
static boolean |
isLocked(Directory directory)
Returns
true iff the index in the named directory is
currently locked. |
int |
maxDoc()
Returns total number of docs in this index, including
docs not yet flushed (still in the RAM buffer),
not counting deletions.
|
void |
maybeMerge()
Expert: asks the mergePolicy whether any merges are
necessary now and if so, runs the requested merges and
then iterate (test again if merges are needed) until no
more merges are returned by the mergePolicy.
|
void |
merge(MergePolicy.OneMerge merge)
Merges the indicated segments, replacing them in the stack with a
single segment.
|
int |
numDeletedDocs(SegmentCommitInfo info)
Obtain the number of deleted docs for a pooled reader.
|
int |
numDocs()
Returns total number of docs in this index, including
docs not yet flushed (still in the RAM buffer), and
including deletions.
|
int |
numRamDocs()
Expert: Return the number of documents currently
buffered in RAM.
|
void |
prepareCommit()
Expert: prepare for commit.
|
long |
ramSizeInBytes()
Expert: Return the total size of all index files currently cached in memory.
|
void |
rollback()
Close the
IndexWriter without committing
any changes that have occurred since the last commit
(or since it was opened, if commit hasn't been called). |
String |
segString()
Returns a string description of all segments, for
debugging.
|
String |
segString(Iterable<SegmentCommitInfo> infos)
Returns a string description of the specified
segments, for debugging.
|
String |
segString(SegmentCommitInfo info)
Returns a string description of the specified
segment, for debugging.
|
void |
setCommitData(Map<String,String> commitUserData)
Sets the commit user data map.
|
boolean |
tryDeleteDocument(IndexReader readerIn,
int docID)
Expert: attempts to delete by document ID, as long as
the provided reader is a near-real-time reader (from
DirectoryReader.open(IndexWriter,boolean) ). |
static void |
unlock(Directory directory)
Forcibly unlocks the index in the named directory.
|
void |
updateBinaryDocValue(Term term,
String field,
BytesRef value)
|
void |
updateDocument(Term term,
Iterable<? extends IndexableField> doc)
Updates a document by first deleting the document(s)
containing
term and then adding the new
document. |
void |
updateDocument(Term term,
Iterable<? extends IndexableField> doc,
Analyzer analyzer)
Updates a document by first deleting the document(s)
containing
term and then adding the new
document. |
void |
updateDocuments(Term delTerm,
Iterable<? extends Iterable<? extends IndexableField>> docs)
Atomically deletes documents matching the provided
delTerm and adds a block of documents with sequentially
assigned document IDs, such that an external reader
will see all or none of the documents.
|
void |
updateDocuments(Term delTerm,
Iterable<? extends Iterable<? extends IndexableField>> docs,
Analyzer analyzer)
Atomically deletes documents matching the provided
delTerm and adds a block of documents, analyzed using
the provided analyzer, with sequentially
assigned document IDs, such that an external reader
will see all or none of the documents.
|
void |
updateNumericDocValue(Term term,
String field,
Long value)
|
void |
waitForMerges()
Wait for any currently outstanding merges to finish.
|
public static final String WRITE_LOCK_NAME
public static final String SOURCE
diagnostics
.public static final String SOURCE_MERGE
public static final String SOURCE_FLUSH
public static final String SOURCE_ADDINDEXES_READERS
addIndexes(IndexReader...)
.public static final int MAX_TERM_LENGTH
IllegalArgumentException
is thrown
and a message is printed to infoStream, if set (see IndexWriterConfig.setInfoStream(InfoStream)
).public IndexWriter(Directory d, IndexWriterConfig conf) throws IOException
conf
.
If you want to make "live" changes to this writer instance, use
getConfig()
.
NOTE: after ths writer is created, the given configuration instance
cannot be passed to another writer. If you intend to do so, you should
clone
it beforehand.
d
- the index directory. The index is either created or appended
according conf.getOpenMode()
.conf
- the configuration settings according to which IndexWriter should
be initialized.IOException
- if the directory cannot be read/written to, or if it does not
exist and conf.getOpenMode()
is
OpenMode.APPEND
or if there is any other low-level
IO errorpublic int numDeletedDocs(SegmentCommitInfo info)
protected final void ensureOpen(boolean failIfClosing) throws AlreadyClosedException
AlreadyClosedException
if this
IndexWriter has been closed or is in the process of closing.failIfClosing
- if true, also fail when IndexWriter
is in the process of
closing (closing=true
) but not yet done closing (
closed=false
)AlreadyClosedException
- if this IndexWriter is closed or in the process of closingprotected final void ensureOpen() throws AlreadyClosedException
AlreadyClosedException
if this IndexWriter has been
closed (closed=true
) or is in the process of
closing (closing=true
).
Calls ensureOpen(true)
.
AlreadyClosedException
- if this IndexWriter is closedpublic LiveIndexWriterConfig getConfig()
LiveIndexWriterConfig
, which can be used to query the IndexWriter
current settings, as well as modify "live" ones.public void close() throws IOException
This is a "slow graceful shutdown" which may take a long time
especially if a big merge is pending: If you only want to close
resources use rollback()
. If you only want to commit
pending changes and close resources see close(boolean)
.
Note that this may be a costly
operation, so, try to re-use a single writer instead of
closing and opening a new one. See commit()
for
caveats about write caching done by some IO devices.
If an Exception is hit during close, eg due to disk full or some other reason, then both the on-disk index and the internal state of the IndexWriter instance will be consistent. However, the close will not be complete even though part of it (flushing buffered documents) may have succeeded, so the write lock will still be held.
If you can correct the underlying cause (eg free up some disk space) then you can call close() again. Failing that, if you want to force the write lock to be released (dangerous, because you may then lose buffered docs in the IndexWriter instance) then you can do something like this:
try { writer.close(); } finally { if (IndexWriter.isLocked(directory)) { IndexWriter.unlock(directory); } }after which, you must be certain not to use the writer instance anymore.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer, again. See above for details.
close
in interface Closeable
close
in interface AutoCloseable
IOException
- if there is a low-level IO errorpublic void close(boolean waitForMerges) throws IOException
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer, again. See above for details.
NOTE: it is dangerous to always call close(false), especially when IndexWriter is not open for very long, because this can result in "merge starvation" whereby long merges will never have a chance to finish. This will cause too many segments in your index over time.
waitForMerges
- if true, this call will block
until all merges complete; else, it will ask all
running merges to abort, wait until those merges have
finished (which should be at most a few seconds), and
then return.IOException
public Directory getDirectory()
public Analyzer getAnalyzer()
public int maxDoc()
numDocs()
public int numDocs()
commit()
first.numDocs()
public boolean hasDeletions()
public void addDocument(Iterable<? extends IndexableField> doc) throws IOException
Note that if an Exception is hit (for example disk full) then the index will be consistent, but this document may not have been added. Furthermore, it's possible the index will have one segment in non-compound format even when using compound files (when a merge has partially succeeded).
This method periodically flushes pending documents
to the Directory (see above), and
also periodically triggers segment merges in the index
according to the MergePolicy
in use.
Merges temporarily consume space in the
directory. The amount of space required is up to 1X the
size of all segments being merged, when no
readers/searchers are open against the index, and up to
2X the size of all segments being merged when
readers/searchers are open against the index (see
forceMerge(int)
for details). The sequence of
primitive merge operations performed is governed by the
merge policy.
Note that each term in the document can be no longer
than MAX_TERM_LENGTH
in bytes, otherwise an
IllegalArgumentException will be thrown.
Note that it's possible to create an invalid Unicode string in java if a UTF16 surrogate pair is malformed. In this case, the invalid characters are silently replaced with the Unicode replacement character U+FFFD.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void addDocument(Iterable<? extends IndexableField> doc, Analyzer analyzer) throws IOException
getAnalyzer()
.
See addDocument(Iterable)
for details on
index and IndexWriter state after an Exception, and
flushing/merging temporary free space requirements.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void addDocuments(Iterable<? extends Iterable<? extends IndexableField>> docs) throws IOException
WARNING: the index does not currently record which documents were added as a block. Today this is fine, because merging will preserve a block. The order of documents within a segment will be preserved, even when child documents within a block are deleted. Most search features (like result grouping and block joining) require you to mark documents; when these documents are deleted these search features will not work as expected. Obviously adding documents to an existing block will require you the reindex the entire block.
However it's possible that in the future Lucene may merge more aggressively re-order documents (for example, perhaps to obtain better index compression), in which case you may need to fully re-index your documents at that time.
See addDocument(Iterable)
for details on
index and IndexWriter state after an Exception, and
flushing/merging temporary free space requirements.
NOTE: tools that do offline splitting of an index (for example, IndexSplitter in contrib) or re-sorting of documents (for example, IndexSorter in contrib) are not aware of these atomically added documents and will likely break them up. Use such tools at your own risk!
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void addDocuments(Iterable<? extends Iterable<? extends IndexableField>> docs, Analyzer analyzer) throws IOException
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void updateDocuments(Term delTerm, Iterable<? extends Iterable<? extends IndexableField>> docs) throws IOException
addDocuments(Iterable)
.CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void updateDocuments(Term delTerm, Iterable<? extends Iterable<? extends IndexableField>> docs, Analyzer analyzer) throws IOException
addDocuments(Iterable)
.CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void deleteDocuments(Term term) throws IOException
term
.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
term
- the term to identify the documents to be deletedCorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic boolean tryDeleteDocument(IndexReader readerIn, int docID) throws IOException
DirectoryReader.open(IndexWriter,boolean)
). If the
provided reader is an NRT reader obtained from this
writer, and its segment has not been merged away, then
the delete succeeds and this method returns true; else, it
returns false the caller must then separately delete by
Term or Query.
NOTE: this method can only delete documents
visible to the currently open NRT reader. If you need
to delete documents indexed after opening the NRT
reader you must use the other deleteDocument methods
(e.g., deleteDocuments(Term)
).IOException
public void deleteDocuments(Term... terms) throws IOException
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
terms
- array of terms to identify the documents
to be deletedCorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void deleteDocuments(Query query) throws IOException
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
query
- the query to identify the documents to be deletedCorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void deleteDocuments(Query... queries) throws IOException
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
queries
- array of queries to identify the documents
to be deletedCorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void updateDocument(Term term, Iterable<? extends IndexableField> doc) throws IOException
term
and then adding the new
document. The delete and then add are atomic as seen
by a reader on the same index (flush may happen only after
the add).
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
term
- the term to identify the document(s) to be
deleteddoc
- the document to be addedCorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void updateDocument(Term term, Iterable<? extends IndexableField> doc, Analyzer analyzer) throws IOException
term
and then adding the new
document. The delete and then add are atomic as seen
by a reader on the same index (flush may happen only after
the add).
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
term
- the term to identify the document(s) to be
deleteddoc
- the document to be addedanalyzer
- the analyzer to use when analyzing the documentCorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void updateNumericDocValue(Term term, String field, Long value) throws IOException
NumericDocValues
for field
to the
given value
. This method can be used to 'unset' a document's
value by passing null
as the new value. Also, you can only update
fields that already exist in the index, not add new fields through this
method.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
term
- the term to identify the document(s) to be updatedfield
- field name of the NumericDocValues
fieldvalue
- new value for the fieldCorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void updateBinaryDocValue(Term term, String field, BytesRef value) throws IOException
BinaryDocValues
for field
to the
given value
. This method can be used to 'unset' a document's
value by passing null
as the new value. Also, you can only update
fields that already exist in the index, not add new fields through this
method.
NOTE: this method currently replaces the existing value of all affected documents with the new value.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
term
- the term to identify the document(s) to be updatedfield
- field name of the BinaryDocValues
fieldvalue
- new value for the fieldCorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorpublic void forceMerge(int maxNumSegments) throws IOException
MergePolicy
.
This is a horribly costly operation, especially when
you pass a small maxNumSegments
; usually you
should only call this if the index is static (will no
longer be changed).
Note that this requires up to 2X the index size free
space in your Directory (3X if you're using compound
file format). For example, if your index size is 10 MB
then you need up to 20 MB free for this to complete (30
MB if you're using compound file format). Also,
it's best to call commit()
afterwards,
to allow IndexWriter to free up disk space.
If some but not all readers re-open while merging is underway, this will cause > 2X temporary space to be consumed as those new readers will then hold open the temporary segments at that time. It is best not to re-open readers while merging is running.
The actual temporary usage could be much less than these figures (it depends on many factors).
In general, once this completes, the total size of the index will be less than the size of the starting index. It could be quite a bit smaller (if there were many pending deletes) or just slightly smaller.
If an Exception is hit, for example due to disk full, the index will not be corrupted and no documents will be lost. However, it may have been partially merged (some segments were merged but not all), and it's possible that one of the segments in the index will be in non-compound format even when using compound file format. This will occur when the Exception is hit during conversion of the segment into compound format.
This call will merge those segments present in the index when the call started. If other threads are still adding documents and flushing segments, those newly created segments will not be merged unless you call forceMerge again.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
NOTE: if you call close(boolean)
with false, which aborts all running merges,
then any thread still running this method might hit a
MergePolicy.MergeAbortedException
.
maxNumSegments
- maximum number of segments left
in the index after merging finishesCorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorMergePolicy.findMerges(org.apache.lucene.index.MergeTrigger, org.apache.lucene.index.SegmentInfos)
public void forceMerge(int maxNumSegments, boolean doWait) throws IOException
forceMerge(int)
, except you can
specify whether the call should block until
all merging completes. This is only meaningful with a
MergeScheduler
that is able to run merges in
background threads.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
IOException
public void forceMergeDeletes(boolean doWait) throws IOException
forceMergeDeletes()
, except you can
specify whether the call should block until the
operation completes. This is only meaningful with a
MergeScheduler
that is able to run merges in
background threads.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
NOTE: if you call close(boolean)
with false, which aborts all running merges,
then any thread still running this method might hit a
MergePolicy.MergeAbortedException
.
IOException
public void forceMergeDeletes() throws IOException
MergePolicy
. For example,
the default TieredMergePolicy
will only
pick a segment if the percentage of
deleted docs is over 10%.
This is often a horribly costly operation; rarely is it warranted.
To see how
many deletions you have pending in your index, call
IndexReader.numDeletedDocs()
.
NOTE: this method first flushes a new segment (if there are indexed documents), and applies all buffered deletes.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
IOException
public final void maybeMerge() throws IOException
MergePolicy
with
MergeTrigger.EXPLICIT
.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
IOException
public Collection<SegmentCommitInfo> getMergingSegments()
MergePolicy
to avoid
selecting merges for segments already being merged.
The returned collection is not cloned, and thus is
only safe to access if you hold IndexWriter's lock
(which you do when IndexWriter invokes the
MergePolicy).
Do not alter the returned collection!
public MergePolicy.OneMerge getNextMerge()
MergeScheduler
calls this method to retrieve the next
merge requested by the MergePolicypublic boolean hasPendingMerges()
public void rollback() throws IOException
IndexWriter
without committing
any changes that have occurred since the last commit
(or since it was opened, if commit hasn't been called).
This removes any temporary files that had been created,
after which the state of the index will be the same as
it was when commit() was last called or when this
writer was first opened. This also clears a previous
call to prepareCommit()
.rollback
in interface TwoPhaseCommit
IOException
- if there is a low-level IO errorpublic void deleteAll() throws IOException
This method will drop all buffered documents and will
remove all segments from the index. This change will not be
visible until a commit()
has been called. This method
can be rolled back using rollback()
.
NOTE: this method is much faster than using deleteDocuments( new MatchAllDocsQuery() ).
Yet, this method also has different semantics compared to deleteDocuments(Query)
/ deleteDocuments(Query...)
since internal data-structures are cleared as well
as all segment information is forcefully dropped anti-viral semantics like omitting norms
are reset or doc value types are cleared. Essentially a call to deleteAll()
is equivalent
to creating a new IndexWriter
with IndexWriterConfig.OpenMode.CREATE
which a delete query only marks
documents as deleted.
NOTE: this method will forcefully abort all merges
in progress. If other threads are running forceMerge(int)
, addIndexes(IndexReader[])
or
forceMergeDeletes(boolean)
methods, they may receive
MergePolicy.MergeAbortedException
s.
IOException
public void waitForMerges()
It is guaranteed that any merges started prior to calling this method will have completed once this method completes.
public void addIndexes(Directory... dirs) throws IOException
This may be used to parallelize batch indexing. A large document collection can be broken into sub-collections. Each sub-collection can be indexed in parallel, on a different thread, process or machine. The complete index can then be created by merging sub-collection indexes with this method.
NOTE: this method acquires the write lock in
each directory, to ensure that no IndexWriter
is currently open or tries to open while this is
running.
This method is transactional in how Exceptions are handled: it does not commit a new segments_N file until all indexes are added. This means if an Exception occurs (for example disk full), then either no indexes will have been added or they all will have been.
Note that this requires temporary free space in the
Directory
up to 2X the sum of all input indexes
(including the starting index). If readers/searchers
are open against the starting index, then temporary
free space required will be higher by the size of the
starting index (see forceMerge(int)
for details).
NOTE: this method only copies the segments of the incoming indexes and does not merge them. Therefore deleted documents are not removed and the new segments are not merged with the existing ones.
This requires this index not be among those to be added.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorLockObtainFailedException
- if we were unable to
acquire the write lock in at least one directorypublic void addIndexes(IndexReader... readers) throws IOException
The provided IndexReaders are not closed.
See addIndexes(org.apache.lucene.store.Directory...)
for details on transactional semantics, temporary
free space required in the Directory, and non-CFS segments on an Exception.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
NOTE: empty segments are dropped by this method and not added to this index.
NOTE: this method merges all given IndexReader
s in one
merge. If you intend to merge a large number of readers, it may be better
to call this method multiple times, each time with a small set of readers.
In principle, if you use a merge policy with a mergeFactor
or
maxMergeAtOnce
parameter, you should pass that many readers in one
call. Also, if the given readers are DirectoryReader
s, they can be
opened with termIndexInterval=-1
to save RAM, since during merge
the in-memory structure is not used. See
DirectoryReader.open(Directory, int)
.
NOTE: if you call close(boolean)
with false, which
aborts all running merges, then any thread still running this method might
hit a MergePolicy.MergeAbortedException
.
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorprotected void doAfterFlush() throws IOException
IOException
protected void doBeforeFlush() throws IOException
IOException
public final void prepareCommit() throws IOException
Expert: prepare for commit. This does the
first phase of 2-phase commit. This method does all
steps necessary to commit changes since this writer
was opened: flushes pending added and deleted docs,
syncs the index files, writes most of next segments_N
file. After calling this you must call either commit()
to finish the commit, or rollback()
to revert the commit and undo all changes
done since the writer was opened.
You can also just call commit()
directly
without prepareCommit first in which case that method
will internally call prepareCommit.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
prepareCommit
in interface TwoPhaseCommit
IOException
public final void setCommitData(Map<String,String> commitUserData)
IndexWriter
and will be committed
even if no other
changes were made to the writer instance. Note that you must call this method
before prepareCommit()
, or otherwise it won't be included in the
follow-on commit()
.
NOTE: the map is cloned internally, therefore altering the map's contents after calling this method has no effect.
public final Map<String,String> getCommitData()
setCommitData(Map)
.public final void commit() throws IOException
Commits all pending changes (added & deleted documents, segment merges, added indexes, etc.) to the index, and syncs all referenced index files, such that a reader will see the changes and the index updates will survive an OS or machine crash or power loss. Note that this does not wait for any running background merges to finish. This may be a costly operation, so you should test the cost in your application and do it only when really necessary.
Note that this operation calls Directory.sync on the index files. That call should not return until the file contents & metadata are on stable storage. For FSDirectory, this calls the OS's fsync. But, beware: some hardware devices may in fact cache writes even during fsync, and return before the bits are actually on stable storage, to give the appearance of faster performance. If you have such a device, and it does not have a battery backup (for example) then on power loss it may still lose data. Lucene cannot guarantee consistency on such devices.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
commit
in interface TwoPhaseCommit
IOException
prepareCommit()
public final boolean hasUncommittedChanges()
commit()
, or a concurrent
merged finished, this method may return true right
after you had just called commit()
.protected final void flush(boolean triggerMerge, boolean applyAllDeletes) throws IOException
triggerMerge
- if true, we may merge segments (if
deletes or docs were flushed) if necessaryapplyAllDeletes
- whether pending deletes should alsoIOException
public final long ramSizeInBytes()
public final int numRamDocs()
public void merge(MergePolicy.OneMerge merge) throws IOException
IOException
public String segString()
public String segString(Iterable<SegmentCommitInfo> infos)
public String segString(SegmentCommitInfo info)
public static boolean isLocked(Directory directory) throws IOException
true
iff the index in the named directory is
currently locked.directory
- the directory to check for a lockIOException
- if there is a low-level IO errorpublic static void unlock(Directory directory) throws IOException
Caution: this should only be used by failure recovery code, when it is known that no other process nor thread is in fact currently accessing this index.
IOException
public void deleteUnusedFiles() throws IOException
IndexWriter normally deletes unused files itself, during indexing. However, on Windows, which disallows deletion of open files, if there is a reader open on the index then those files cannot be deleted. This is fine, because IndexWriter will periodically retry the deletion.
However, IndexWriter doesn't try that often: only on open, close, flushing a new segment, and finishing a merge. If you don't do any of these actions with your IndexWriter, you'll see the unused files linger. If that's a problem, call this method to delete them (once you've closed the open readers that were preventing their deletion).
In addition, you can call this method to delete
unreferenced index commits. This might be useful if you
are using an IndexDeletionPolicy
which holds
onto index commits until some criteria are met, but those
commits are no longer needed. Otherwise, those commits will
be deleted the next time commit() is called.
IOException
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