An IndexWriter creates and maintains an index. The create argument to the constructor determines whether a new index is created, or whether an existing index is opened. Note that you can open an index with create=true 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. There are also constructors with no create argument which 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(Document) and removed with DeleteDocuments(Term) or DeleteDocuments(Query). A document can be updated with UpdateDocument(Term, Document) (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 buffered deletes (see SetMaxBufferedDeleteTerms) or enough added documents since the last flush, whichever is sooner. For the added documents, flushing is triggered either by RAM usage of the documents (see SetRAMBufferSizeMB) or the number of added documents. The default is to flush when RAM usage hits 16 MB. For best indexing speed you should flush by RAM usage with a large RAM buffer. 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). If an index will not have more documents added for a while and optimal search performance is desired, then either the full Optimize() method or partial Optimize(int) method should be called before the index is closed. 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. More...

Inherits IDisposable.

Classes
class	IndexReaderWarmer
	If GetReader() 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. This is not required for near real-time search, but will reduce search latency on opening a new near real-time reader after a merge completes. More...

class	MaxFieldLength
	Specifies maximum field length (in number of tokens/terms) in IndexWriter constructors. SetMaxFieldLength(int) overrides the value set by the constructor. More...

class	ReaderPool
	Holds shared SegmentReader instances. IndexWriter uses SegmentReaders for 1) applying deletes, 2) doing merges, 3) handing out a real-time reader. This pool reuses instances of the SegmentReaders in all these places if it is in "near real-time mode" (getReader() has been called on this instance).

Public Member Functions
virtual IndexReader	GetReader ()
	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 Commit().

virtual IndexReader	GetReader (int termInfosIndexDivisor)
	Expert: like GetReader(), except you can specify which termInfosIndexDivisor should be used for any newly opened readers.

virtual int	NumDeletedDocs (SegmentInfo info)
	Obtain the number of deleted docs for a pooled reader. If the reader isn't being pooled, the segmentInfo's delCount is returned.

virtual void	Message (System.String message)
	Prints a message to the infoStream (if non-null), prefixed with the identifying information for this writer and the thread that's calling it.

virtual void	SetSimilarity (Similarity similarity)
	Expert: Set the Similarity implementation used by this IndexWriter.

	IndexWriter (Directory d, Analyzer a, bool create, MaxFieldLength mfl)
	Constructs an IndexWriter for the index in `d`. Text will be analyzed with `a`. If `create` is true, then a new, empty index will be created in `d`, replacing the index already there, if any.

	IndexWriter (Directory d, Analyzer a, MaxFieldLength mfl)
	Constructs an IndexWriter for the index in `d`, first creating it if it does not already exist.

	IndexWriter (Directory d, Analyzer a, IndexDeletionPolicy deletionPolicy, MaxFieldLength mfl)
	Expert: constructs an IndexWriter with a custom IndexDeletionPolicy , for the index in `d`, first creating it if it does not already exist. Text will be analyzed with `a`.

	IndexWriter (Directory d, Analyzer a, bool create, IndexDeletionPolicy deletionPolicy, MaxFieldLength mfl)
	Expert: constructs an IndexWriter with a custom IndexDeletionPolicy , for the index in `d`. Text will be analyzed with `a`. If `create` is true, then a new, empty index will be created in `d`, replacing the index already there, if any.

	IndexWriter (Directory d, Analyzer a, IndexDeletionPolicy deletionPolicy, MaxFieldLength mfl, IndexCommit commit)
	Expert: constructs an IndexWriter on specific commit point, with a custom IndexDeletionPolicy, for the index in `d`. Text will be analyzed with `a`.

virtual void	SetMergePolicy (MergePolicy mp)
	Expert: set the merge policy used by this writer.

virtual void	SetMergeScheduler (MergeScheduler mergeScheduler)
	Expert: set the merge scheduler used by this writer.

virtual void	SetMaxFieldLength (int maxFieldLength)
	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 DEFAULT_MAX_FIELD_LENGTH terms will be indexed for a field.

virtual int	GetMaxFieldLength ()
	Returns the maximum number of terms that will be indexed for a single field in a document.

virtual void	SetMaxBufferedDocs (int maxBufferedDocs)
	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.

virtual int	GetMaxBufferedDocs ()
	Returns the number of buffered added documents that will trigger a flush if enabled.

virtual void	SetRAMBufferSizeMB (double mb)
	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.

virtual double	GetRAMBufferSizeMB ()
	Returns the value set by SetRAMBufferSizeMB if enabled.

virtual void	SetMaxBufferedDeleteTerms (int maxBufferedDeleteTerms)
	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).

virtual int	GetMaxBufferedDeleteTerms ()
	Returns the number of buffered deleted terms that will trigger a flush if enabled.

virtual void	SetInfoStream (System.IO.StreamWriter infoStream)
	If non-null, information about merges, deletes and a message when maxFieldLength is reached will be printed to this.

void	Close ()
	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 Commit() for caveats about write caching done by some IO devices.

virtual void	Dispose ()
	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 Commit() for caveats about write caching done by some IO devices.

virtual void	Dispose (bool waitForMerges)
	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.

virtual void	Close (bool waitForMerges)
	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.

virtual int	MaxDoc ()
	Returns total number of docs in this index, including docs not yet flushed (still in the RAM buffer), not counting deletions.

virtual int	NumDocs ()
	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 Commit() first.

virtual bool	HasDeletions ()

virtual void	AddDocument (Document doc)
	Adds a document to this index. If the document contains more than SetMaxFieldLength(int) terms for a given field, the remainder are discarded.

virtual void	AddDocument (Document doc, Analyzer analyzer)
	Adds a document to this index, using the provided analyzer instead of the value of Analyzer. If the document contains more than SetMaxFieldLength(int) terms for a given field, the remainder are discarded.

virtual void	DeleteDocuments (Term term)
	Deletes the document(s) containing `term`.

virtual void	DeleteDocuments (params Term[] terms)
	Deletes the document(s) containing any of the terms. All deletes are flushed at the same time.

virtual void	DeleteDocuments (Query query)
	Deletes the document(s) matching the provided query.

virtual void	DeleteDocuments (params Query[] queries)
	Deletes the document(s) matching any of the provided queries. All deletes are flushed at the same time.

virtual void	UpdateDocument (Term term, Document doc)
	Updates a document by first deleting the document(s) containing `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).

virtual void	UpdateDocument (Term term, Document doc, Analyzer analyzer)
	Updates a document by first deleting the document(s) containing `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).

int	GetDocCount (int i)

virtual void	Optimize ()
	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.

virtual void	Optimize (int maxNumSegments)
	Optimize the index down to <= maxNumSegments. If maxNumSegments==1 then this is the same as Optimize()

virtual void	Optimize (bool doWait)
	Just like Optimize(), except you can specify whether the call should block until the optimize completes. This is only meaningful with a MergeScheduler that is able to run merges in background threads.

virtual void	Optimize (int maxNumSegments, bool doWait)
	Just like Optimize(int), except you can specify whether the call should block until the optimize completes. This is only meaningful with a MergeScheduler that is able to run merges in background threads.

virtual void	ExpungeDeletes (bool doWait)
	Just like ExpungeDeletes(), 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.

virtual void	ExpungeDeletes ()
	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 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 MergePolicy; see Index.MergePolicy.FindMergesToExpungeDeletes.). Note that this call does not first commit any buffered documents, so you must do so yourself if necessary. See also See Also ExpungeDeletes(bool)

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.

virtual 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). 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().

virtual void	DeleteAll ()
	Delete all documents in the index.

virtual void	WaitForMerges ()
	Wait for any currently outstanding merges to finish.

virtual void	AddIndexesNoOptimize (params Directory[] dirs)
	Merges all segments from an array of indexes into this index.

virtual void	AddIndexes (params IndexReader[] readers)
	Merges the provided indexes into this index. After this completes, the index is optimized. The provided IndexReaders are not closed.

void	PrepareCommit ()
	Expert: prepare for commit.

void	Commit ()
	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.

void	Commit (IDictionary< string, string > commitUserData)
	Commits all changes to the index, specifying a commitUserData Map (String -> String). This just calls PrepareCommit(IDictionary{string, string}) (if you didn't already call it) and then FinishCommit.

void	Flush (bool triggerMerge, bool flushDocStores, bool flushDeletes)
	Flush all in-memory buffered udpates (adds and deletes) to the Directory.

long	RamSizeInBytes ()
	Expert: Return the total size of all index files currently cached in memory. Useful for size management with flushRamDocs()

int	NumRamDocs ()
	Expert: Return the number of documents currently buffered in RAM.

void	Merge_ForNUnit (MergePolicy.OneMerge merge)

virtual SegmentInfo	NewestSegment ()

virtual System.String	SegString ()

virtual bool	TestPoint (System.String name)

Static Public Member Functions
static bool	IsLocked (Directory directory)
	Returns `true` iff the index in the named directory is currently locked.

static void	Unlock (Directory directory)
	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 Attributes
const System.String	WRITE_LOCK_NAME = "write.lock"
	Name of the write lock in the index.

const int	DISABLE_AUTO_FLUSH = - 1
	Value to denote a flush trigger is disabled

const double	DEFAULT_RAM_BUFFER_SIZE_MB = 16.0
	Default value is 16 MB (which means flush when buffered docs consume 16 MB RAM). Change using SetRAMBufferSizeMB.

const int	DEFAULT_MAX_FIELD_LENGTH = 10000
	Default value is 10,000. Change using SetMaxFieldLength(int).

const int	DEFAULT_TERM_INDEX_INTERVAL = 128
	Default value is 128. Change using TermIndexInterval.

Static Public Attributes
static long	WRITE_LOCK_TIMEOUT = 1000
	Default value for the write lock timeout (1,000).

static readonly int	DEFAULT_MAX_BUFFERED_DOCS = DISABLE_AUTO_FLUSH
	Disabled by default (because IndexWriter flushes by RAM usage by default). Change using SetMaxBufferedDocs(int).

static readonly int	DEFAULT_MAX_BUFFERED_DELETE_TERMS = DISABLE_AUTO_FLUSH
	Disabled by default (because IndexWriter flushes by RAM usage by default). Change using SetMaxBufferedDeleteTerms(int).

static readonly int	MAX_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 SetInfoStream).

Protected Member Functions
virtual void	Dispose (bool disposing, bool waitForMerges)

virtual void	DoAfterFlush ()

virtual void	DoBeforeFlush ()

Properties
virtual bool	UseCompoundFile `[get, set]`
	Gets or sets 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.

virtual Similarity	Similarity `[get]`
	Expert: Return the Similarity implementation used by this IndexWriter.

virtual int	TermIndexInterval `[get, set]`
	Expert: Gets or sets 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.

virtual MergePolicy	MergePolicy `[get]`
	Expert: returns the current MergePolicy in use by this writer.

virtual MergeScheduler	MergeScheduler `[get]`
	Expert: returns the current MergePolicy in use by this writer.

virtual int	MaxMergeDocs `[get, set]`
	Gets or sets 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 int.MaxValue. Note that this method is a convenience method: it just calls mergePolicy.getMaxMergeDocs as long as mergePolicy is an instance of LogMergePolicy. Otherwise an IllegalArgumentException is thrown.

int	ReaderTermsIndexDivisor `[get, set]`

virtual int	MergeFactor `[get, set]`
	Gets or sets the number of segments that are merged at once and also controls the total number of segments allowed to accumulate in the index. 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.

static StreamWriter	DefaultInfoStream `[get, set]`
	Gets or sets the default info stream. If non-null, this will be the default infoStream used by a newly instantiated IndexWriter.

virtual StreamWriter	InfoStream `[get]`
	Returns the current infoStream in use by this writer.

virtual bool	Verbose `[get]`
	Returns true if verbosing is enabled (i.e., infoStream != null).

virtual long	WriteLockTimeout `[get, set]`
	Gets or sets allowed timeout when acquiring the write lock.

static long	DefaultWriteLockTimeout `[get, set]`
	Gets or sets the default (for any instance of IndexWriter) maximum time to wait for a write lock (in milliseconds).

virtual Directory	Directory `[get]`
	Returns the Directory used by this index.

virtual Analyzer	Analyzer `[get]`
	Returns the analyzer used by this index.

virtual IndexReaderWarmer	MergedSegmentWarmer `[get, set]`
	Gets or sets the merged segment warmer. See IndexReaderWarmer

Detailed Description

An IndexWriter creates and maintains an index.

The create argument to the constructor determines whether a new index is created, or whether an existing index is opened. Note that you can open an index with create=true 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. There are also constructors with no create argument which 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(Document) and removed with DeleteDocuments(Term) or DeleteDocuments(Query). A document can be updated with UpdateDocument(Term, Document) (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 buffered deletes (see SetMaxBufferedDeleteTerms) or enough added documents since the last flush, whichever is sooner. For the added documents, flushing is triggered either by RAM usage of the documents (see SetRAMBufferSizeMB) or the number of added documents. The default is to flush when RAM usage hits 16 MB. For best indexing speed you should flush by RAM usage with a large RAM buffer. 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).

If an index will not have more documents added for a while and optimal search performance is desired, then either the full Optimize() method or partial Optimize(int) method should be called before the index is closed.

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 Index.MergePolicy.MergeSpecification describing the merges. It also selects merges to do for optimize(). (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 System.Threading.ThreadInterruptedException and clear the interrupt status on the thread

Definition at line 160 of file IndexWriter.cs.

Constructor & Destructor Documentation

Lucene.Net.Index.IndexWriter.IndexWriter	(	Directory	d,
		Analyzer	a,
		bool	create,
		MaxFieldLength	mfl
	)

Constructs an IndexWriter for the index in d. Text will be analyzed with a. If create is true, then a new, empty index will be created in d, replacing the index already there, if any.

Parameters

d	the index directory
a	the analyzer to use
create	`true` to create the index or overwrite the existing one; `false` to append to the existing index
mfl	Maximum field length in number of terms/tokens: LIMITED, UNLIMITED, or user-specified via the MaxFieldLength constructor.

<throws> CorruptIndexException if the index is corrupt </throws> <throws> LockObtainFailedException if another writer </throws>

has this index open (write.lock could not be obtained)

<throws> IOException if the directory cannot be read/written to, or </throws>

if it does not exist and create is false or if there is any other low-level IO error

Definition at line 1015 of file IndexWriter.cs.

Lucene.Net.Index.IndexWriter.IndexWriter	(	Directory	d,
		Analyzer	a,
		MaxFieldLength	mfl
	)

Constructs an IndexWriter for the index in d, first creating it if it does not already exist.

Parameters

d	the index directory
a	the analyzer to use
mfl	Maximum field length in number of terms/tokens: LIMITED, UNLIMITED, or user-specified via the MaxFieldLength constructor.

<throws> CorruptIndexException if the index is corrupt </throws> <throws> LockObtainFailedException if another writer </throws>

has this index open (write.lock could not be obtained)

<throws> IOException if the directory cannot be </throws>

read/written to or if there is any other low-level IO error

Definition at line 1042 of file IndexWriter.cs.

Lucene.Net.Index.IndexWriter.IndexWriter	(	Directory	d,
		Analyzer	a,
		IndexDeletionPolicy	deletionPolicy,
		MaxFieldLength	mfl
	)

Expert: constructs an IndexWriter with a custom IndexDeletionPolicy , for the index in d, first creating it if it does not already exist. Text will be analyzed with a.

Parameters

d	the index directory
a	the analyzer to use
deletionPolicy	see above
mfl	whether or not to limit field lengths

<throws> CorruptIndexException if the index is corrupt </throws> <throws> LockObtainFailedException if another writer </throws>

has this index open (write.lock could not be obtained)

<throws> IOException if the directory cannot be </throws>

read/written to or if there is any other low-level IO error

Definition at line 1071 of file IndexWriter.cs.

Lucene.Net.Index.IndexWriter.IndexWriter	(	Directory	d,
		Analyzer	a,
		bool	create,
		IndexDeletionPolicy	deletionPolicy,
		MaxFieldLength	mfl
	)

Expert: constructs an IndexWriter with a custom IndexDeletionPolicy , for the index in d. Text will be analyzed with a. If create is true, then a new, empty index will be created in d, replacing the index already there, if any.

Parameters

d	the index directory
a	the analyzer to use
create	`true` to create the index or overwrite the existing one; `false` to append to the existing index
deletionPolicy	see above
mfl	Lucene.Net.Index.IndexWriter.MaxFieldLength, whether or not to limit field lengths. Value is in number of terms/tokens

<throws> CorruptIndexException if the index is corrupt </throws> <throws> LockObtainFailedException if another writer </throws>

has this index open (write.lock could not be obtained)

<throws> IOException if the directory cannot be read/written to, or </throws>

if it does not exist and create is false or if there is any other low-level IO error

Definition at line 1107 of file IndexWriter.cs.

Lucene.Net.Index.IndexWriter.IndexWriter	(	Directory	d,
		Analyzer	a,
		IndexDeletionPolicy	deletionPolicy,
		MaxFieldLength	mfl,
		IndexCommit	commit
	)

Expert: constructs an IndexWriter on specific commit point, with a custom IndexDeletionPolicy, for the index in d. Text will be analyzed with a.

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

This operation is similar to 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 IndexDeletionPolicy has preserved past commits.

Parameters

d	the index directory
a	the analyzer to use
deletionPolicy	see above
mfl	whether or not to limit field lengths, value is in number of terms/tokens. See Lucene.Net.Index.IndexWriter.MaxFieldLength.
commit	which commit to open

<throws> CorruptIndexException if the index is corrupt </throws> <throws> LockObtainFailedException if another writer </throws>

has this index open (write.lock could not be obtained)

<throws> IOException if the directory cannot be read/written to, or </throws>

if it does not exist and create is false or if there is any other low-level IO error

Definition at line 1193 of file IndexWriter.cs.

Member Function Documentation

virtual void Lucene.Net.Index.IndexWriter.AddDocument ( Document doc )

virtual

Adds a document to this index. If the document contains more than 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 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 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.

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 2301 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.AddDocument	(	Document	doc,
		Analyzer	analyzer
	)

virtual

Adds a document to this index, using the provided analyzer instead of the value of Analyzer. If the document contains more than SetMaxFieldLength(int) terms for a given field, the remainder are discarded.

See 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.

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 2322 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.AddIndexes ( params IndexReader[] readers )

virtual

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 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.

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws> summary> 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). /summary>

Definition at line 3781 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.AddIndexesNoOptimize ( params Directory[] dirs )

virtual

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 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.

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 3583 of file IndexWriter.cs.

void Lucene.Net.Index.IndexWriter.Close ( )

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 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.

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 1825 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Close ( bool waitForMerges )

virtual

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.

Parameters

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.

Definition at line 1946 of file IndexWriter.cs.

void Lucene.Net.Index.IndexWriter.Commit ( )

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.

See Also: PrepareCommit()

See Also: Commit(IDictionary{string,string})

Definition at line 4081 of file IndexWriter.cs.

void Lucene.Net.Index.IndexWriter.Commit ( IDictionary< string, string > commitUserData )

Commits all changes to the index, specifying a commitUserData Map (String -> String). This just calls PrepareCommit(IDictionary{string, string}) (if you didn't already call it) and then FinishCommit.

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

Definition at line 4095 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.DeleteAll ( )

virtual

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 Commit() has been called. This method can be rolled back using 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 Optimize() or any of the addIndexes methods, they will receive Index.MergePolicy.MergeAbortedExceptions.

Definition at line 3335 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.DeleteDocuments ( Term term )

virtual

Deletes the document(s) containing term.

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

Parameters

term	the term to identify the documents to be deleted

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 2375 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.DeleteDocuments ( params Term[] terms )

virtual

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.

Parameters

terms array of terms to identify the documents to be deleted

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 2403 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.DeleteDocuments ( Query query )

virtual

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.

Parameters

query the query to identify the documents to be deleted

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 2429 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.DeleteDocuments ( params Query[] queries )

virtual

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.

Parameters

queries array of queries to identify the documents to be deleted

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 2450 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Dispose ( )

virtual

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 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.

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 1871 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Dispose ( bool waitForMerges )

virtual

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.

Parameters

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.

Definition at line 1899 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Dispose	(	bool	disposing,
		bool	waitForMerges
	)

protectedvirtual

Definition at line 1904 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.DoAfterFlush ( )

protectedvirtual

summary> A hook for extending classes to execute operations before pending added and deleted documents are flushed to the Directory. /summary>

Definition at line 3964 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.DoBeforeFlush ( )

protectedvirtual

Definition at line 3972 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.ExpungeDeletes ( bool doWait )

virtual

Just like ExpungeDeletes(), 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.

Definition at line 2839 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.ExpungeDeletes ( )

virtual

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 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 MergePolicy; see Index.MergePolicy.FindMergesToExpungeDeletes.). Note that this call does not first commit any buffered documents, so you must do so yourself if necessary. See also

See Also: ExpungeDeletes(bool)

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

Definition at line 2925 of file IndexWriter.cs.

void Lucene.Net.Index.IndexWriter.Flush	(	bool	triggerMerge,
		bool	flushDocStores,
		bool	flushDeletes
	)

Flush all in-memory buffered udpates (adds and deletes) to the Directory.

Parameters

triggerMerge	if true, we may merge segments (if deletes or docs were flushed) if necessary
flushDocStores	if false we are allowed to keep doc stores open to share with the next segment
flushDeletes	whether pending deletes should also be flushed

Definition at line 4178 of file IndexWriter.cs.

int Lucene.Net.Index.IndexWriter.GetDocCount ( int i )

Definition at line 2560 of file IndexWriter.cs.

virtual int Lucene.Net.Index.IndexWriter.GetMaxBufferedDeleteTerms ( )

virtual

Returns the number of buffered deleted terms that will trigger a flush if enabled.

See Also: SetMaxBufferedDeleteTerms

Definition at line 1673 of file IndexWriter.cs.

virtual int Lucene.Net.Index.IndexWriter.GetMaxBufferedDocs ( )

virtual

Returns the number of buffered added documents that will trigger a flush if enabled.

See Also: SetMaxBufferedDocs

Definition at line 1578 of file IndexWriter.cs.

virtual int Lucene.Net.Index.IndexWriter.GetMaxFieldLength ( )

virtual

Returns the maximum number of terms that will be indexed for a single field in a document.

See Also: SetMaxFieldLength

Definition at line 1480 of file IndexWriter.cs.

virtual double Lucene.Net.Index.IndexWriter.GetRAMBufferSizeMB ( )

virtual

Returns the value set by SetRAMBufferSizeMB if enabled.

Definition at line 1640 of file IndexWriter.cs.

virtual IndexReader Lucene.Net.Index.IndexWriter.GetReader ( )

virtual

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 Commit().

Note that this is functionally equivalent to calling {#commit} and then using IndexReader.Open(Lucene.Net.Store.Directory, bool) to open a new reader. But the turarnound time of this method should be faster since it avoids the potentially costly Commit().

You must close the 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 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 MergedSegmentWarmer to call MergedSegmentWarmer 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 AlreadyClosedException.

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

Returns

IndexReader that covers entire index plus all changes made so far by this IndexWriter instance

<throws> IOException </throws>

Definition at line 351 of file IndexWriter.cs.

virtual IndexReader Lucene.Net.Index.IndexWriter.GetReader ( int termInfosIndexDivisor )

virtual

Expert: like GetReader(), except you can specify which termInfosIndexDivisor should be used for any newly opened readers.

Parameters

termInfosIndexDivisor Subsambles which indexed terms are loaded into RAM. This has the same effect as IndexWriter.TermIndexInterval except that setting must be done at indexing time while this setting can be set per reader. When set to N, then one in every N*termIndexInterval terms in the index is loaded into memory. By setting this to a value > 1 you can reduce memory usage, at the expense of higher latency when loading a TermInfo. The default value is 1. Set this to -1 to skip loading the terms index entirely.

Definition at line 371 of file IndexWriter.cs.

virtual bool Lucene.Net.Index.IndexWriter.HasDeletions ( )

virtual

Definition at line 2228 of file IndexWriter.cs.

static bool Lucene.Net.Index.IndexWriter.IsLocked ( Directory directory )

static

Returns true iff the index in the named directory is currently locked.

Parameters

directory the directory to check for a lock

<throws> IOException if there is a low-level IO error </throws>

Definition at line 5763 of file IndexWriter.cs.

virtual int Lucene.Net.Index.IndexWriter.MaxDoc ( )

virtual

Returns total number of docs in this index, including docs not yet flushed (still in the RAM buffer), not counting deletions.

See Also: NumDocs

Definition at line 2185 of file IndexWriter.cs.

void Lucene.Net.Index.IndexWriter.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.

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.

Definition at line 2943 of file IndexWriter.cs.

void Lucene.Net.Index.IndexWriter.Merge_ForNUnit ( MergePolicy.OneMerge merge )

Definition at line 4645 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Message ( System.String message )

virtual

Prints a message to the infoStream (if non-null), prefixed with the identifying information for this writer and the thread that's calling it.

Definition at line 869 of file IndexWriter.cs.

virtual SegmentInfo Lucene.Net.Index.IndexWriter.NewestSegment ( )

virtual

Definition at line 5403 of file IndexWriter.cs.

virtual int Lucene.Net.Index.IndexWriter.NumDeletedDocs ( SegmentInfo info )

virtual

Obtain the number of deleted docs for a pooled reader. If the reader isn't being pooled, the segmentInfo's delCount is returned.

Definition at line 743 of file IndexWriter.cs.

virtual int Lucene.Net.Index.IndexWriter.NumDocs ( )

virtual

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 Commit() first.

See Also: NumDocs

Definition at line 2209 of file IndexWriter.cs.

int Lucene.Net.Index.IndexWriter.NumRamDocs ( )

Expert: Return the number of documents currently buffered in RAM.

Definition at line 4409 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Optimize ( )

virtual

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.

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

See Also: Index.LogMergePolicy.FindMergesForOptimize

Definition at line 2671 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Optimize ( int maxNumSegments )

virtual

Optimize the index down to <= maxNumSegments. If maxNumSegments==1 then this is the same as Optimize()

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

Parameters

maxNumSegments maximum number of segments left in the index after optimization finishes

Definition at line 2688 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Optimize ( bool doWait )

virtual

Just like Optimize(), except you can specify whether the call should block until the optimize 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.

Definition at line 2703 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Optimize	(	int	maxNumSegments,
		bool	doWait
	)

virtual

Just like Optimize(int), except you can specify whether the call should block until the optimize 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.

Definition at line 2718 of file IndexWriter.cs.

void Lucene.Net.Index.IndexWriter.PrepareCommit ( )

Expert: prepare for commit.

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

See Also: PrepareCommit(IDictionary{string,string})

Definition at line 3985 of file IndexWriter.cs.

long Lucene.Net.Index.IndexWriter.RamSizeInBytes ( )

Expert: Return the total size of all index files currently cached in memory. Useful for size management with flushRamDocs()

Definition at line 4400 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.Rollback ( )

virtual

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). 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().

<throws> IOException if there is a low-level IO error </throws>

Definition at line 3230 of file IndexWriter.cs.

virtual System.String Lucene.Net.Index.IndexWriter.SegString ( )

virtual

Definition at line 5408 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.SetInfoStream ( System.IO.StreamWriter infoStream )

virtual

If non-null, information about merges, deletes and a message when maxFieldLength is reached will be printed to this.

Definition at line 1719 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.SetMaxBufferedDeleteTerms ( int maxBufferedDeleteTerms )

virtual

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).

<throws> IllegalArgumentException if maxBufferedDeleteTerms </throws>

is enabled but smaller than 1

See Also: SetRAMBufferSizeMB

Definition at line 1657 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.SetMaxBufferedDocs ( int maxBufferedDocs )

virtual

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 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).

<throws> IllegalArgumentException if maxBufferedDocs is </throws>

enabled but smaller than 2, or it disables maxBufferedDocs when ramBufferSize is already disabled

See Also: SetRAMBufferSizeMB

Definition at line 1534 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.SetMaxFieldLength ( int maxFieldLength )

virtual

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 DEFAULT_MAX_FIELD_LENGTH terms will be indexed for a field.

Definition at line 1465 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.SetMergePolicy ( MergePolicy mp )

virtual

Expert: set the merge policy used by this writer.

Definition at line 1359 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.SetMergeScheduler ( MergeScheduler mergeScheduler )

virtual

Expert: set the merge scheduler used by this writer.

Definition at line 1388 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.SetRAMBufferSizeMB ( double mb )

virtual

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 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 SetMaxBufferedDeleteTerms to flush by count instead of RAM usage (each buffered delete Query counts as one).

NOTE: because IndexWriter uses ints 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 DEFAULT_RAM_BUFFER_SIZE_MB.

<throws> IllegalArgumentException if ramBufferSize is </throws>

enabled but non-positive, or it disables ramBufferSize when maxBufferedDocs is already disabled

Definition at line 1623 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.SetSimilarity ( Similarity similarity )

virtual

Expert: Set the Similarity implementation used by this IndexWriter.

Definition at line 930 of file IndexWriter.cs.

virtual bool Lucene.Net.Index.IndexWriter.TestPoint ( System.String name )

virtual

Definition at line 5887 of file IndexWriter.cs.

static void Lucene.Net.Index.IndexWriter.Unlock ( Directory directory )

static

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.

Definition at line 5774 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.UpdateDocument	(	Term	term,
		Document	doc
	)

virtual

Updates a document by first deleting the document(s) containing 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.

Parameters

term	the term to identify the document(s) to be deleted
doc	the document to be added

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 2476 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.UpdateDocument	(	Term	term,
		Document	doc,
		Analyzer	analyzer
	)

virtual

Updates a document by first deleting the document(s) containing 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.

Parameters

term	the term to identify the document(s) to be deleted
doc	the document to be added
analyzer	the analyzer to use when analyzing the document

<throws> CorruptIndexException if the index is corrupt </throws> <throws> IOException if there is a low-level IO error </throws>

Definition at line 2502 of file IndexWriter.cs.

virtual void Lucene.Net.Index.IndexWriter.WaitForMerges ( )

virtual

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.

Definition at line 3447 of file IndexWriter.cs.

Member Data Documentation

readonly int Lucene.Net.Index.IndexWriter.DEFAULT_MAX_BUFFERED_DELETE_TERMS = DISABLE_AUTO_FLUSH

static

Disabled by default (because IndexWriter flushes by RAM usage by default). Change using SetMaxBufferedDeleteTerms(int).

Definition at line 195 of file IndexWriter.cs.

readonly int Lucene.Net.Index.IndexWriter.DEFAULT_MAX_BUFFERED_DOCS = DISABLE_AUTO_FLUSH

static

Disabled by default (because IndexWriter flushes by RAM usage by default). Change using SetMaxBufferedDocs(int).

Definition at line 185 of file IndexWriter.cs.

const int Lucene.Net.Index.IndexWriter.DEFAULT_MAX_FIELD_LENGTH = 10000

Default value is 10,000. Change using SetMaxFieldLength(int).

Definition at line 198 of file IndexWriter.cs.

const double Lucene.Net.Index.IndexWriter.DEFAULT_RAM_BUFFER_SIZE_MB = 16.0

Default value is 16 MB (which means flush when buffered docs consume 16 MB RAM). Change using SetRAMBufferSizeMB.

Definition at line 190 of file IndexWriter.cs.

const int Lucene.Net.Index.IndexWriter.DEFAULT_TERM_INDEX_INTERVAL = 128

Default value is 128. Change using TermIndexInterval.

Definition at line 201 of file IndexWriter.cs.

const int Lucene.Net.Index.IndexWriter.DISABLE_AUTO_FLUSH = - 1

Value to denote a flush trigger is disabled

Definition at line 180 of file IndexWriter.cs.

readonly int Lucene.Net.Index.IndexWriter.MAX_TERM_LENGTH

static

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 SetInfoStream).

Definition at line 208 of file IndexWriter.cs.

const System.String Lucene.Net.Index.IndexWriter.WRITE_LOCK_NAME = "write.lock"

Name of the write lock in the index.

Definition at line 177 of file IndexWriter.cs.

long Lucene.Net.Index.IndexWriter.WRITE_LOCK_TIMEOUT = 1000

static

Default value for the write lock timeout (1,000).

See Also: DefaultWriteLockTimeout

Definition at line 172 of file IndexWriter.cs.

Property Documentation

virtual Analyzer Lucene.Net.Index.IndexWriter.Analyzer

get

Returns the analyzer used by this index.

Definition at line 2171 of file IndexWriter.cs.

StreamWriter Lucene.Net.Index.IndexWriter.DefaultInfoStream

staticgetset

Gets or sets the default info stream. If non-null, this will be the default infoStream used by a newly instantiated IndexWriter.

See Also: SetInfoStream

Definition at line 1710 of file IndexWriter.cs.

long Lucene.Net.Index.IndexWriter.DefaultWriteLockTimeout

staticgetset

Gets or sets the default (for any instance of IndexWriter) maximum time to wait for a write lock (in milliseconds).

Definition at line 1778 of file IndexWriter.cs.

virtual Directory Lucene.Net.Index.IndexWriter.Directory

get

Returns the Directory used by this index.

Definition at line 2160 of file IndexWriter.cs.

virtual StreamWriter Lucene.Net.Index.IndexWriter.InfoStream

get

Returns the current infoStream in use by this writer.

See Also: SetInfoStream

Definition at line 1745 of file IndexWriter.cs.

virtual int Lucene.Net.Index.IndexWriter.MaxMergeDocs

getset

Gets or sets 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 int.MaxValue. Note that this method is a convenience method: it just calls mergePolicy.getMaxMergeDocs as long as mergePolicy is an instance of LogMergePolicy. Otherwise an IllegalArgumentException is thrown.

The default merge policy (LogByteSizeMergePolicy) also allows you to set this limit by net size (in MB) of the segment, using LogByteSizeMergePolicy.MaxMergeMB.

See Also: MaxMergeDocs

Definition at line 1447 of file IndexWriter.cs.

virtual IndexReaderWarmer Lucene.Net.Index.IndexWriter.MergedSegmentWarmer

getset

Gets or sets the merged segment warmer. See IndexReaderWarmer

Definition at line 5860 of file IndexWriter.cs.

virtual int Lucene.Net.Index.IndexWriter.MergeFactor

getset

Gets or sets the number of segments that are merged at once and also controls the total number of segments allowed to accumulate in the index. 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 LogMergePolicy. Otherwise an IllegalArgumentException is thrown.

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

Definition at line 1698 of file IndexWriter.cs.

virtual MergePolicy Lucene.Net.Index.IndexWriter.MergePolicy

get

Expert: returns the current MergePolicy in use by this writer.

See Also: SetMergePolicy

Definition at line 1379 of file IndexWriter.cs.

virtual MergeScheduler Lucene.Net.Index.IndexWriter.MergeScheduler

get

Expert: returns the current MergePolicy in use by this writer.

See Also: SetMergePolicy

Definition at line 1415 of file IndexWriter.cs.

int Lucene.Net.Index.IndexWriter.ReaderTermsIndexDivisor

getset

Gets or sets the termsIndexDivisor passed to any readers that IndexWriter opens, for example when applying deletes or creating a near-real-time reader in GetReader(). Default value is IndexReader.DEFAULT_TERMS_INDEX_DIVISOR.

Definition at line 1492 of file IndexWriter.cs.

virtual Similarity Lucene.Net.Index.IndexWriter.Similarity

get

Expert: Return the Similarity implementation used by this IndexWriter.

This defaults to the current value of Search.Similarity.Default.

Definition at line 942 of file IndexWriter.cs.

virtual int Lucene.Net.Index.IndexWriter.TermIndexInterval

getset

Expert: Gets or sets 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, numUniqueTerms/interval terms are read into memory by an IndexReader, and, on average, interval/2 terms must be scanned for each random term access.

See Also: DEFAULT_TERM_INDEX_INTERVAL

Definition at line 974 of file IndexWriter.cs.

virtual bool Lucene.Net.Index.IndexWriter.UseCompoundFile

getset

Gets or sets 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 LogMergePolicy. Otherwise an IllegalArgumentException is thrown.

Definition at line 919 of file IndexWriter.cs.

virtual bool Lucene.Net.Index.IndexWriter.Verbose

get

Returns true if verbosing is enabled (i.e., infoStream != null).

Definition at line 1755 of file IndexWriter.cs.

virtual long Lucene.Net.Index.IndexWriter.WriteLockTimeout

getset

Gets or sets allowed timeout when acquiring the write lock.

Definition at line 1761 of file IndexWriter.cs.

The documentation for this class was generated from the following file:

core/Index/IndexWriter.cs

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