The IndexWriter type exposes the following members.

Constructors

  NameDescription
Public methodIndexWriter(FileInfo, Analyzer) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
path
, first creating it if it does not already exist. Text will be analyzed with
CopyC#
a
.
Public methodIndexWriter(String, Analyzer) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
path
, first creating it if it does not already exist. Text will be analyzed with
CopyC#
a
.
Public methodIndexWriter(Directory, Analyzer) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
d
, first creating it if it does not already exist. Text will be analyzed with
CopyC#
a
.
Public methodIndexWriter(FileInfo, Analyzer, IndexWriter..::..MaxFieldLength) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
path
, first creating it if it does not already exist. Text will be analyzed with
CopyC#
a
.

NOTE: autoCommit (see above) is set to false with this constructor.

Public methodIndexWriter(FileInfo, Analyzer, Boolean) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
path
. Text will be analyzed with
CopyC#
a
. If
CopyC#
create
is true, then a new, empty index will be created in
CopyC#
path
, replacing the index already there, if any.
Public methodIndexWriter(String, Analyzer, IndexWriter..::..MaxFieldLength) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
path
, first creating it if it does not already exist. Text will be analyzed with
CopyC#
a
.

NOTE: autoCommit (see above) is set to false with this constructor.

Public methodIndexWriter(String, Analyzer, Boolean) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
path
. Text will be analyzed with
CopyC#
a
. If
CopyC#
create
is true, then a new, empty index will be created in
CopyC#
path
, replacing the index already there, if any.
Public methodIndexWriter(Directory, Analyzer, IndexWriter..::..MaxFieldLength)
Constructs an IndexWriter for the index in
CopyC#
d
, first creating it if it does not already exist. Text will be analyzed with
CopyC#
a
.

NOTE: autoCommit (see above) is set to false with this constructor.

Public methodIndexWriter(Directory, Analyzer, Boolean) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
d
. Text will be analyzed with
CopyC#
a
. If
CopyC#
create
is true, then a new, empty index will be created in
CopyC#
d
, replacing the index already there, if any.
Public methodIndexWriter(Directory, Boolean, Analyzer) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
d
, first creating it if it does not already exist. Text will be analyzed with
CopyC#
a
.
Public methodIndexWriter(FileInfo, Analyzer, Boolean, IndexWriter..::..MaxFieldLength) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
path
. Text will be analyzed with
CopyC#
a
. If
CopyC#
create
is true, then a new, empty index will be created in
CopyC#
path
, replacing the index already there, if any.

NOTE: autoCommit (see above) is set to false with this constructor.

Public methodIndexWriter(String, Analyzer, Boolean, IndexWriter..::..MaxFieldLength) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
path
. Text will be analyzed with
CopyC#
a
. If
CopyC#
create
is true, then a new, empty index will be created in
CopyC#
path
, replacing the index already there, if any.

NOTE: autoCommit (see above) is set to false with this constructor.

Public methodIndexWriter(Directory, Analyzer, IndexDeletionPolicy, IndexWriter..::..MaxFieldLength)
Expert: constructs an IndexWriter with a custom {@link IndexDeletionPolicy}, for the index in
CopyC#
d
, first creating it if it does not already exist. Text will be analyzed with
CopyC#
a
.

NOTE: autoCommit (see above) is set to false with this constructor.

Public methodIndexWriter(Directory, Analyzer, Boolean, IndexWriter..::..MaxFieldLength)
Constructs an IndexWriter for the index in
CopyC#
d
. Text will be analyzed with
CopyC#
a
. If
CopyC#
create
is true, then a new, empty index will be created in
CopyC#
d
, replacing the index already there, if any.

NOTE: autoCommit (see above) is set to false with this constructor.

Public methodIndexWriter(Directory, Boolean, Analyzer, IndexDeletionPolicy) Obsolete.
Expert: constructs an IndexWriter with a custom {@link IndexDeletionPolicy}, for the index in
CopyC#
d
, first creating it if it does not already exist. Text will be analyzed with
CopyC#
a
.
Public methodIndexWriter(Directory, Boolean, Analyzer, Boolean) Obsolete.
Constructs an IndexWriter for the index in
CopyC#
d
. Text will be analyzed with
CopyC#
a
. If
CopyC#
create
is true, then a new, empty index will be created in
CopyC#
d
, replacing the index already there, if any.
Public methodIndexWriter(Directory, Analyzer, IndexDeletionPolicy, IndexWriter..::..MaxFieldLength, IndexCommit)
Expert: constructs an IndexWriter on specific commit point, with a custom {@link IndexDeletionPolicy}, for the index in
CopyC#
d
. Text will be analyzed with
CopyC#
a
.

This is only meaningful if you've used a {@link IndexDeletionPolicy} in that past that keeps more than just the last commit.

This operation is similar to {@link #Rollback()}, except that method can only rollback what's been done with the current instance of IndexWriter since its last commit, whereas this method can rollback to an arbitrary commit point from the past, assuming the {@link IndexDeletionPolicy} has preserved past commits.

NOTE: autoCommit (see above) is set to false with this constructor.

Public methodIndexWriter(Directory, Analyzer, Boolean, IndexDeletionPolicy, IndexWriter..::..MaxFieldLength)
Expert: constructs an IndexWriter with a custom {@link IndexDeletionPolicy}, for the index in
CopyC#
d
. Text will be analyzed with
CopyC#
a
. If
CopyC#
create
is true, then a new, empty index will be created in
CopyC#
d
, replacing the index already there, if any.

NOTE: autoCommit (see above) is set to false with this constructor.

Public methodIndexWriter(Directory, Boolean, Analyzer, Boolean, IndexDeletionPolicy) Obsolete.
Expert: constructs an IndexWriter with a custom {@link IndexDeletionPolicy}, for the index in
CopyC#
d
. Text will be analyzed with
CopyC#
a
. If
CopyC#
create
is true, then a new, empty index will be created in
CopyC#
d
, replacing the index already there, if any.

Methods

  NameDescription
Public methodAbort Obsolete.
Public methodAddDocument(Document)
Adds a document to this index. If the document contains more than {@link #SetMaxFieldLength(int)} terms for a given field, the remainder are discarded.

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 {@link 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 {@link #Optimize()} 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 16383 characters, 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.

Public methodAddDocument(Document, Analyzer)
Adds a document to this index, using the provided analyzer instead of the value of {@link #GetAnalyzer()}. If the document contains more than {@link #SetMaxFieldLength(int)} terms for a given field, the remainder are discarded.

See {@link #AddDocument(Document)} 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.

Public methodAddIndexes(array<Directory>[]()[][]) Obsolete.
Merges all segments from an array of indexes into this index.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodAddIndexes(array<IndexReader>[]()[][])
Merges the provided indexes into this index.

After this completes, the index is optimized.

The provided IndexReaders are not closed.

NOTE: while this is running, any attempts to add or delete documents (with another thread) will be paused until this method completes.

See {@link #AddIndexesNoOptimize(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.

Public methodAddIndexesNoOptimize
Merges all segments from an array of indexes into this index.

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: the index in each Directory must not be changed (opened by a writer) while this method is running. This method does not acquire a write lock in each input Directory, so it is up to the caller to enforce this.

NOTE: while this is running, any attempts to add or delete documents (with another thread) will be paused until this method completes.

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 {@link #Optimize()} for details).

Once this completes, the final size of the index will be less than the sum of all input index sizes (including the starting index). It could be quite a bit smaller (if there were many pending deletes) or just slightly smaller.

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.

Public methodClose()()()()
Commits all changes to an index and closes all associated files. 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 {@link #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.

Public methodClose(Boolean)
Closes the index with or without waiting for currently running merges to finish. This is only meaningful when using a MergeScheduler that runs merges in background threads.

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.

Public methodCommit()()()()

Commits all pending changes (added & deleted documents, optimizations, 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.

Public methodCommit(IDictionary<(Of <<'(String, String>)>>))
Commits all changes to the index, specifying a commitUserData Map (String -> String). This just calls {@link #PrepareCommit(Map)} (if you didn't already call it) and then {@link #finishCommit}.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodDeleteAll
Delete all documents in the index.

This method will drop all buffered documents and will remove all segments from the index. This change will not be visible until a {@link #Commit()} has been called. This method can be rolled back using {@link #Rollback()}.

NOTE: this method is much faster than using deleteDocuments( new MatchAllDocsQuery() ).

NOTE: this method will forcefully abort all merges in progress. If other threads are running {@link #Optimize()} or any of the addIndexes methods, they will receive {@link MergePolicy.MergeAbortedException}s.

Public methodDeleteDocuments(Query)
Deletes the document(s) matching the provided query.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodDeleteDocuments(array<Query>[]()[][])
Deletes the document(s) matching any of the provided queries. All deletes are flushed at the same time.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodDeleteDocuments(Term)
Deletes the document(s) containing
CopyC#
term
.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodDeleteDocuments(array<Term>[]()[][])
Deletes the document(s) containing any of the terms. All deletes are flushed at the same time.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodDispose
.NET
Protected methodDoAfterFlush
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 methodDoBeforeFlush
A hook for extending classes to execute operations before pending added and deleted documents are flushed to the Directory.
Public methodDocCount Obsolete.
Returns the number of documents currently in this index, not counting deletions.
Protected methodEnsureOpen()()()()
Protected methodEnsureOpen(Boolean)
Used internally to throw an {@link AlreadyClosedException} if this IndexWriter has been closed.
Public methodEquals
Determines whether the specified Object is equal to the current Object.
(Inherited from Object.)
Public methodExpungeDeletes()()()()
Expunges all deletes from the index. When an index has many document deletions (or updates to existing documents), it's best to either call optimize or expungeDeletes to remove all unused data in the index associated with the deleted documents. To see how many deletions you have pending in your index, call {@link IndexReader#numDeletedDocs} This saves disk space and memory usage while searching. expungeDeletes should be somewhat faster than optimize since it does not insist on reducing the index to a single segment (though, this depends on the {@link MergePolicy}; see {@link MergePolicy#findMergesToExpungeDeletes}.). Note that this call does not first commit any buffered documents, so you must do so yourself if necessary. See also {@link #ExpungeDeletes(boolean)}

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodExpungeDeletes(Boolean)
Just like {@link #ExpungeDeletes()}, except you can specify whether the call should block until the operation completes. This is only meaningful with a {@link 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.

Protected methodFinalize
Allows an Object to attempt to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection.
(Inherited from Object.)
Public methodFlush()()()() Obsolete.
Flush all in-memory buffered updates (adds and deletes) to the Directory.

Note: while this will force buffered docs to be pushed into the index, it will not make these docs visible to a reader. Use {@link #Commit()} instead

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodFlush(Boolean, Boolean, Boolean)
Flush all in-memory buffered udpates (adds and deletes) to the Directory.
Public methodGetAnalyzer
Returns the analyzer used by this index.
Public methodGetBufferedDeleteTermsSize
Public methodStatic memberGetDefaultInfoStream
Returns the current default infoStream for newly instantiated IndexWriters.
Public methodStatic memberGetDefaultWriteLockTimeout
Returns default write lock timeout for newly instantiated IndexWriters.
Public methodGetDirectory
Returns the Directory used by this index.
Public methodGetDocCount
Public methodGetFlushCount
Public methodGetFlushDeletesCount
Public methodGetHashCode
Serves as a hash function for a particular type.
(Inherited from Object.)
Public methodGetInfoStream
Returns the current infoStream in use by this writer.
Public methodGetMaxBufferedDeleteTerms
Returns the number of buffered deleted terms that will trigger a flush if enabled.
Public methodGetMaxBufferedDocs
Returns the number of buffered added documents that will trigger a flush if enabled.
Public methodGetMaxFieldLength
Returns the maximum number of terms that will be indexed for a single field in a document.
Public methodGetMaxMergeDocs

Returns the largest segment (measured by document count) that may be merged with other segments.

Note that this method is a convenience method: it just calls mergePolicy.getMaxMergeDocs as long as mergePolicy is an instance of {@link LogMergePolicy}. Otherwise an IllegalArgumentException is thrown.

Public methodGetMaxSyncPauseSeconds Obsolete.
Expert: returns max delay inserted before syncing a commit point. On Windows, at least, pausing before syncing can increase net indexing throughput. The delay is variable based on size of the segment's files, and is only inserted when using ConcurrentMergeScheduler for merges.
Public methodGetMergedSegmentWarmer
Returns the current merged segment warmer. See {@link IndexReaderWarmer}.
Public methodGetMergeFactor

Returns the number of segments that are merged at once and also controls the total number of segments allowed to accumulate in the index.

Note that this method is a convenience method: it just calls mergePolicy.getMergeFactor as long as mergePolicy is an instance of {@link LogMergePolicy}. Otherwise an IllegalArgumentException is thrown.

Public methodGetMergePolicy
Expert: returns the current MergePolicy in use by this writer.
Public methodGetMergeScheduler
Expert: returns the current MergePolicy in use by this writer.
Public methodGetNextMerge_forNUnit
Public methodGetNumBufferedDeleteTerms
Public methodGetNumBufferedDocuments
Public methodGetRAMBufferSizeMB
Returns the value set by {@link #setRAMBufferSizeMB} if enabled.
Public methodGetReader()()()()
Expert: returns a readonly reader, covering all committed as well as un-committed changes to the index. This provides "near real-time" searching, in that changes made during an IndexWriter session can be quickly made available for searching without closing the writer nor calling {@link #commit}.

Note that this is functionally equivalent to calling {#commit} and then using {@link IndexReader#open} to open a new reader. But the turarnound time of this method should be faster since it avoids the potentially costly {@link #commit}.

You must close the {@link IndexReader} returned by this method once you are done using it.

It's near real-time because there is no hard guarantee on how quickly you can get a new reader after making changes with IndexWriter. You'll have to experiment in your situation to determine if it's faster enough. As this is a new and experimental feature, please report back on your findings so we can learn, improve and iterate.

The resulting reader suppports {@link IndexReader#reopen}, but that call will simply forward back to this method (though this may change in the future).

The very first time this method is called, this writer instance will make every effort to pool the readers that it opens for doing merges, applying deletes, etc. This means additional resources (RAM, file descriptors, CPU time) will be consumed.

For lower latency on reopening a reader, you should call {@link #setMergedSegmentWarmer} to call {@link #setMergedSegmentWarmer} to pre-warm a newly merged segment before it's committed to the index. This is important for minimizing index-to-search delay after a large merge.

If an addIndexes* call is running in another thread, then this reader will only search those segments from the foreign index that have been successfully copied over, so far

.

NOTE: Once the writer is closed, any outstanding readers may continue to be used. However, if you attempt to reopen any of those readers, you'll hit an {@link AlreadyClosedException}.

NOTE: This API is experimental and might change in incompatible ways in the next release.

Public methodGetReader(Int32)
Expert: like {@link #getReader}, except you can specify which termInfosIndexDivisor should be used for any newly opened readers.
Public methodGetReaderTermsIndexDivisor
Public methodGetSegmentCount
Public methodGetSimilarity
Expert: Return the Similarity implementation used by this IndexWriter.

This defaults to the current value of {@link Similarity#GetDefault()}.

Public methodGetTermIndexInterval
Expert: Return the interval between indexed terms.
Public methodGetType
Gets the Type of the current instance.
(Inherited from Object.)
Public methodGetUseCompoundFile

Get the current setting of whether newly flushed segments will use the compound file format. Note that this just returns the value previously set with setUseCompoundFile(boolean), or the default value (true). You cannot use this to query the status of previously flushed segments.

Note that this method is a convenience method: it just calls mergePolicy.getUseCompoundFile as long as mergePolicy is an instance of {@link LogMergePolicy}. Otherwise an IllegalArgumentException is thrown.

Public methodGetWriteLockTimeout
Returns allowed timeout when acquiring the write lock.
Public methodHasDeletions
Public methodStatic memberIsLocked(String) Obsolete.
Returns
CopyC#
true
iff the index in the named directory is currently locked.
Public methodStatic memberIsLocked(Directory)
Returns
CopyC#
true
iff the index in the named directory is currently locked.
Public methodMaxDoc
Returns total number of docs in this index, including docs not yet flushed (still in the RAM buffer), not counting deletions.
Public methodMaybeMerge
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. Explicit calls to maybeMerge() are usually not necessary. The most common case is when merge policy parameters have changed.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Protected methodMemberwiseClone
Creates a shallow copy of the current Object.
(Inherited from Object.)
Public methodMerge_ForNUnit
Public methodMessage
Prints a message to the infoStream (if non-null), prefixed with the identifying information for this writer and the thread that's calling it.
Public methodNewestSegment
Public methodNumDeletedDocs
Obtain the number of deleted docs for a pooled reader. If the reader isn't being pooled, the segmentInfo's delCount is returned.
Public methodNumDocs
Returns total number of docs in this index, including docs not yet flushed (still in the RAM buffer), and including deletions. NOTE: buffered deletions are not counted. If you really need these to be counted you should call {@link #Commit()} first.
Public methodNumRamDocs
Expert: Return the number of documents currently buffered in RAM.
Public methodOptimize()()()()
Requests an "optimize" operation on an index, priming the index for the fastest available search. Traditionally this has meant merging all segments into a single segment as is done in the default merge policy, but individaul merge policies may implement optimize in different ways.

It is recommended that this method be called upon completion of indexing. In environments with frequent updates, optimize is best done during low volume times, if at all.

See http://www.gossamer-threads.com/lists/lucene/java-dev/47895 for more discussion.

Note that optimize requires 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 20 MB free for optimize to complete (30 MB if you're using compound fiel format).

If some but not all readers re-open while an optimize is underway, this will cause > 2X temporary space to be consumed as those new readers will then hold open the partially optimized segments at that time. It is best not to re-open readers while optimize is running.

The actual temporary usage could be much less than these figures (it depends on many factors).

In general, once the optimize 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 during optimize(), for example due to disk full, the index will not be corrupt and no documents will have been lost. However, it may have been partially optimized (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 optimize 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 optimized unless you call optimize again.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodOptimize(Boolean)
Just like {@link #Optimize()}, except you can specify whether the call should block until the optimize completes. This is only meaningful with a {@link 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.

Public methodOptimize(Int32)
Optimize the index down to <= maxNumSegments. If maxNumSegments==1 then this is the same as {@link #Optimize()}.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodOptimize(Int32, Boolean)
Just like {@link #Optimize(int)}, except you can specify whether the call should block until the optimize completes. This is only meaningful with a {@link 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.

Public methodPrepareCommit()()()()
Expert: prepare for commit.

NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.

Public methodPrepareCommit(IDictionary<(Of <<'(String, String>)>>))

Expert: prepare for commit, specifying commitUserData Map (String -> String). This does the first phase of 2-phase commit. You can only call this when autoCommit is false. 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 {@link #Commit()} to finish the commit, or {@link #Rollback()} to revert the commit and undo all changes done since the writer was opened.

You can also just call {@link #Commit(Map)} 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.

Public methodRamSizeInBytes
Expert: Return the total size of all index files currently cached in memory. Useful for size management with flushRamDocs()
Public methodRollback
Close the
CopyC#
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 can only be called when this IndexWriter was opened with
CopyC#
autoCommit=false
. This also clears a previous call to {@link #prepareCommit}.
Public methodSegString
Public methodSetAllowMinus1Position
Deprecated: emulates IndexWriter's buggy behavior when first token(s) have positionIncrement==0 (ie, prior to fixing LUCENE-1542)
Public methodStatic memberSetDefaultInfoStream
If non-null, this will be the default infoStream used by a newly instantiated IndexWriter.
Public methodStatic memberSetDefaultWriteLockTimeout
Sets the default (for any instance of IndexWriter) maximum time to wait for a write lock (in milliseconds).
Public methodSetInfoStream
If non-null, information about merges, deletes and a message when maxFieldLength is reached will be printed to this.
Public methodSetMaxBufferedDeleteTerms

Determines the minimal number of delete terms required before the buffered in-memory delete terms are applied and flushed. If there are documents buffered in memory at the time, they are merged and a new segment is created.

Disabled by default (writer flushes by RAM usage).

Public methodSetMaxBufferedDocs
Determines the minimal number of documents required before the buffered in-memory documents are flushed as a new Segment. Large values generally gives faster indexing.

When this is set, the writer will flush every maxBufferedDocs added documents. Pass in {@link #DISABLE_AUTO_FLUSH} to prevent triggering a flush due to number of buffered documents. Note that if flushing by RAM usage is also enabled, then the flush will be triggered by whichever comes first.

Disabled by default (writer flushes by RAM usage).

Public methodSetMaxFieldLength
The maximum number of terms that will be indexed for a single field in a document. This limits the amount of memory required for indexing, so that collections with very large files will not crash the indexing process by running out of memory. This setting refers to the number of running terms, not to the number of different terms.

Note: this silently truncates large documents, excluding from the index all terms that occur further in the document. If you know your source documents are large, be sure to set this value high enough to accomodate the expected size. If you set it to Integer.MAX_VALUE, then the only limit is your memory, but you should anticipate an OutOfMemoryError.

By default, no more than {@link #DEFAULT_MAX_FIELD_LENGTH} terms will be indexed for a field.

Public methodSetMaxMergeDocs

Determines the largest segment (measured by document count) that may be merged with other segments. Small values (e.g., less than 10,000) are best for interactive indexing, as this limits the length of pauses while indexing to a few seconds. Larger values are best for batched indexing and speedier searches.

The default value is {@link Integer#MAX_VALUE}.

Note that this method is a convenience method: it just calls mergePolicy.setMaxMergeDocs as long as mergePolicy is an instance of {@link LogMergePolicy}. Otherwise an IllegalArgumentException is thrown.

The default merge policy ({@link LogByteSizeMergePolicy}) also allows you to set this limit by net size (in MB) of the segment, using {@link LogByteSizeMergePolicy#setMaxMergeMB}.

Public methodSetMaxSyncPauseSeconds Obsolete.
Expert: sets the max delay before syncing a commit point.
Public methodSetMergedSegmentWarmer
Set the merged segment warmer. See {@link IndexReaderWarmer}.
Public methodSetMergeFactor
Determines how often segment indices are merged by addDocument(). With smaller values, less RAM is used while indexing, and searches on unoptimized indices are faster, but indexing speed is slower. With larger values, more RAM is used during indexing, and while searches on unoptimized indices are slower, indexing is faster. Thus larger values (> 10) are best for batch index creation, and smaller values (< 10) for indices that are interactively maintained.

Note that this method is a convenience method: it just calls mergePolicy.setMergeFactor as long as mergePolicy is an instance of {@link LogMergePolicy}. Otherwise an IllegalArgumentException is thrown.

This must never be less than 2. The default value is 10.

Public methodSetMergePolicy
Expert: set the merge policy used by this writer.
Public methodSetMergeScheduler
Expert: set the merge scheduler used by this writer.
Public methodSetRAMBufferSizeMB
Determines the amount of RAM that may be used for buffering added documents and deletions before they are flushed to the Directory. Generally for faster indexing performance it's best to flush by RAM usage instead of document count and use as large a RAM buffer as you can.

When this is set, the writer will flush whenever buffered documents and deletions use this much RAM. Pass in {@link #DISABLE_AUTO_FLUSH} to prevent triggering a flush due to RAM usage. Note that if flushing by document count is also enabled, then the flush will be triggered by whichever comes first.

NOTE: the account of RAM usage for pending deletions is only approximate. Specifically, if you delete by Query, Lucene currently has no way to measure the RAM usage if individual Queries so the accounting will under-estimate and you should compensate by either calling commit() periodically yourself, or by using {@link #setMaxBufferedDeleteTerms} to flush by count instead of RAM usage (each buffered delete Query counts as one).

NOTE: because IndexWriter uses

CopyC#
int
s when managing its internal storage, the absolute maximum value for this setting is somewhat less than 2048 MB. The precise limit depends on various factors, such as how large your documents are, how many fields have norms, etc., so it's best to set this value comfortably under 2048.

The default value is {@link #DEFAULT_RAM_BUFFER_SIZE_MB}.

Public methodSetReaderTermsIndexDivisor
Public methodSetSimilarity
Expert: Set the Similarity implementation used by this IndexWriter.
Public methodSetTermIndexInterval
Expert: Set the interval between indexed terms. Large values cause less memory to be used by IndexReader, but slow random-access to terms. Small values cause more memory to be used by an IndexReader, and speed random-access to terms. This parameter determines the amount of computation required per query term, regardless of the number of documents that contain that term. In particular, it is the maximum number of other terms that must be scanned before a term is located and its frequency and position information may be processed. In a large index with user-entered query terms, query processing time is likely to be dominated not by term lookup but rather by the processing of frequency and positional data. In a small index or when many uncommon query terms are generated (e.g., by wildcard queries) term lookup may become a dominant cost. In particular,
CopyC#
numUniqueTerms/interval
terms are read into memory by an IndexReader, and, on average,
CopyC#
interval/2
terms must be scanned for each random term access.
Public methodSetUseCompoundFile

Setting to turn on usage of a compound file. When on, multiple files for each segment are merged into a single file when a new segment is flushed.

Note that this method is a convenience method: it just calls mergePolicy.setUseCompoundFile as long as mergePolicy is an instance of {@link LogMergePolicy}. Otherwise an IllegalArgumentException is thrown.

Public methodSetWriteLockTimeout
Public methodTestPoint
Public methodToString
Returns a String that represents the current Object.
(Inherited from Object.)
Public methodStatic memberUnlock
Forcibly unlocks the index in the named directory.

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.

Public methodUpdateDocument(Term, Document)
Updates a document by first deleting the document(s) containing
CopyC#
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.

Public methodUpdateDocument(Term, Document, Analyzer)
Updates a document by first deleting the document(s) containing
CopyC#
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.

Public methodVerbose
Returns true if verbosing is enabled (i.e., infoStream != null).
Public methodWaitForMerges
Wait for any currently outstanding merges to finish.

It is guaranteed that any merges started prior to calling this method will have completed once this method completes.

Fields

  NameDescription
Public fieldStatic memberDEFAULT_MAX_BUFFERED_DELETE_TERMS
Disabled by default (because IndexWriter flushes by RAM usage by default). Change using {@link #SetMaxBufferedDeleteTerms(int)}.
Public fieldStatic memberDEFAULT_MAX_BUFFERED_DOCS
Disabled by default (because IndexWriter flushes by RAM usage by default). Change using {@link #SetMaxBufferedDocs(int)}.
Public fieldStatic memberDEFAULT_MAX_FIELD_LENGTH
Default value is 10,000. Change using {@link #SetMaxFieldLength(int)}.
Public fieldStatic memberDEFAULT_MAX_MERGE_DOCS Obsolete.
Public fieldStatic memberDEFAULT_MAX_SYNC_PAUSE_SECONDS
Default for {@link #getMaxSyncPauseSeconds}. On Windows this defaults to 10.0 seconds; elsewhere it's 0.
Public fieldStatic memberDEFAULT_MERGE_FACTOR Obsolete.
Public fieldStatic memberDEFAULT_RAM_BUFFER_SIZE_MB
Default value is 16 MB (which means flush when buffered docs consume 16 MB RAM). Change using {@link #setRAMBufferSizeMB}.
Public fieldStatic memberDEFAULT_TERM_INDEX_INTERVAL
Default value is 128. Change using {@link #SetTermIndexInterval(int)}.
Public fieldStatic memberDISABLE_AUTO_FLUSH
Value to denote a flush trigger is disabled
Public fieldStatic memberMAX_TERM_LENGTH
Absolute hard maximum length for a term. If a term arrives from the analyzer longer than this length, it is skipped and a message is printed to infoStream, if set (see {@link #setInfoStream}).
Public fieldStatic memberWRITE_LOCK_NAME
Name of the write lock in the index.
Public fieldStatic memberWRITE_LOCK_TIMEOUT
Default value for the write lock timeout (1,000).

See Also