java.lang.Object | |
↳ | org.apache.lucene.index.IndexWriter |
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
and removed with deleteDocuments(Term)
or deleteDocuments(Query)
. A document can be updated with updateDocument
(which just deletes
and then adds the entire document). When finished adding, deleting
and updating documents, close
should be called.
These changes are buffered in memory and periodically
flushed to the Directory
(during the above method
calls). A flush is triggered when there are enough
buffered deletes (see setMaxBufferedDeleteTerms(int)
)
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(double)
) 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 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 ThreadInterruptedException
and clear the interrupt status on the thread.
Nested Classes | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
IndexWriter.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. |
||||||||||
IndexWriter.MaxFieldLength | Specifies maximum field length (in number of tokens/terms) in IndexWriter constructors. |
Constants | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
int | DEFAULT_MAX_BUFFERED_DELETE_TERMS | Disabled by default (because IndexWriter flushes by RAM usage by default). | |||||||||
int | DEFAULT_MAX_BUFFERED_DOCS | Disabled by default (because IndexWriter flushes by RAM usage by default). | |||||||||
int | DEFAULT_MAX_FIELD_LENGTH | Default value is 10,000. | |||||||||
double | DEFAULT_RAM_BUFFER_SIZE_MB | Default value is 16 MB (which means flush when buffered docs consume 16 MB RAM). | |||||||||
int | DEFAULT_TERM_INDEX_INTERVAL | Default value is 128. | |||||||||
int | DISABLE_AUTO_FLUSH | Value to denote a flush trigger is disabled | |||||||||
int | MAX_TERM_LENGTH | Absolute hard maximum length for a term. | |||||||||
String | WRITE_LOCK_NAME | Name of the write lock in the index. |
Fields | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
WRITE_LOCK_TIMEOUT | Default value for the write lock timeout (1,000). |
Public Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Constructs an IndexWriter for the index in
d . | |||||||||||
Constructs an IndexWriter for the index in
d , first creating it if it does not
already exist. | |||||||||||
Expert: constructs an IndexWriter with a custom
IndexDeletionPolicy , for the index in d ,
first creating it if it does not already exist. | |||||||||||
Expert: constructs an IndexWriter with a custom
IndexDeletionPolicy , for the index in d . | |||||||||||
Expert: constructs an IndexWriter on specific commit
point, with a custom
IndexDeletionPolicy , for
the index in d . |
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Adds a document to this index, using the provided analyzer instead of the
value of
getAnalyzer() . | |||||||||||
Adds a document to this index.
| |||||||||||
Merges the provided indexes into this index.
| |||||||||||
Merges all segments from an array of indexes into this
index.
| |||||||||||
Commits all changes to an index and closes all
associated files.
| |||||||||||
Closes the index with or without waiting for currently
running merges to finish.
| |||||||||||
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. | |||||||||||
Commits all changes to the index, specifying a
commitUserData Map (String -> String).
| |||||||||||
Delete all documents in the index.
| |||||||||||
Deletes the document(s) matching any of the provided queries.
| |||||||||||
Deletes the document(s) matching the provided query.
| |||||||||||
Deletes the document(s) containing any of the
terms.
| |||||||||||
Deletes the document(s) containing
term . | |||||||||||
Just like
expungeDeletes() , except you can
specify whether the call should block until the
operation completes. | |||||||||||
Expunges all deletes from the index.
| |||||||||||
Returns the analyzer used by this index.
| |||||||||||
Returns the current default infoStream for newly
instantiated IndexWriters.
| |||||||||||
Returns default write lock timeout for newly
instantiated IndexWriters.
| |||||||||||
Returns the Directory used by this index.
| |||||||||||
Returns the current infoStream in use by this writer.
| |||||||||||
Returns the number of buffered deleted terms that will
trigger a flush if enabled.
| |||||||||||
Returns the number of buffered added documents that will
trigger a flush if enabled.
| |||||||||||
Returns the maximum number of terms that will be
indexed for a single field in a document.
| |||||||||||
Returns the largest segment (measured by document count) that may be merged with other segments. | |||||||||||
Returns the number of segments that are merged at once and also controls the total number of segments allowed to accumulate in the index. | |||||||||||
Expert: returns the current MergePolicy in use by this writer.
| |||||||||||
Expert: returns the current MergePolicy in use by this
writer.
| |||||||||||
Returns the current merged segment warmer.
| |||||||||||
Returns the value set by
setRAMBufferSizeMB(double) if enabled. | |||||||||||
Expert: returns a readonly reader, covering all
committed as well as un-committed changes to the index.
| |||||||||||
Expert: like
getReader() , except you can
specify which termInfosIndexDivisor should be used for
any newly opened readers. | |||||||||||
Expert: Return the Similarity implementation used by this IndexWriter.
| |||||||||||
Expert: Return the interval between indexed terms.
| |||||||||||
Get the current setting of whether newly flushed segments will use the compound file format. | |||||||||||
Returns allowed timeout when acquiring the write lock.
| |||||||||||
Returns
true iff the index in the named directory is
currently locked. | |||||||||||
Returns total number of docs in this index, including
docs not yet flushed (still in the RAM buffer),
not counting deletions.
| |||||||||||
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.
| |||||||||||
Prints a message to the infoStream (if non-null),
prefixed with the identifying information for this
writer and the thread that's calling it.
| |||||||||||
Obtain the number of deleted docs for a pooled reader.
| |||||||||||
Returns total number of docs in this index, including
docs not yet flushed (still in the RAM buffer), and
including deletions.
| |||||||||||
Expert: Return the number of documents currently
buffered in RAM.
| |||||||||||
Optimize the index down to <= maxNumSegments.
| |||||||||||
Just like
optimize(int) , except you can
specify whether the call should block until the
optimize completes. | |||||||||||
Just like
optimize() , except you can specify
whether the call should block until the optimize
completes. | |||||||||||
Requests an "optimize" operation on an index, priming the index
for the fastest available search.
| |||||||||||
Expert: prepare for commit, specifying commitUserData Map (String -> String). | |||||||||||
Expert: prepare for commit.
| |||||||||||
Expert: Return the total size of all index files currently cached in memory.
| |||||||||||
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). | |||||||||||
If non-null, this will be the default infoStream used
by a newly instantiated IndexWriter.
| |||||||||||
Sets the default (for any instance of IndexWriter) maximum time to wait for a write lock (in
milliseconds).
| |||||||||||
If non-null, information about merges, deletes and a
message when maxFieldLength is reached will be printed
to this.
| |||||||||||
Determines the minimal number of delete terms required before the buffered in-memory delete terms are applied and flushed. | |||||||||||
Determines the minimal number of documents required
before the buffered in-memory documents are flushed as
a new Segment.
| |||||||||||
The maximum number of terms that will be indexed for a single field in a
document.
| |||||||||||
Determines the largest segment (measured by document count) that may be merged with other segments. | |||||||||||
Determines how often segment indices are merged by addDocument().
| |||||||||||
Expert: set the merge policy used by this writer.
| |||||||||||
Expert: set the merge scheduler used by this writer.
| |||||||||||
Set the merged segment warmer.
| |||||||||||
Determines the amount of RAM that may be used for
buffering added documents and deletions before they are
flushed to the Directory.
| |||||||||||
Sets the termsIndexDivisor passed to any readers that
IndexWriter opens, for example when applying deletes
or creating a near-real-time reader in
getReader() . | |||||||||||
Expert: Set the Similarity implementation used by this IndexWriter.
| |||||||||||
Expert: Set the interval between indexed terms.
| |||||||||||
Setting to turn on usage of a compound file. | |||||||||||
Sets the maximum time to wait for a write lock (in milliseconds) for this instance of IndexWriter.
| |||||||||||
Forcibly unlocks the index in the named directory.
| |||||||||||
Updates a document by first deleting the document(s)
containing
term and then adding the new
document. | |||||||||||
Updates a document by first deleting the document(s)
containing
term and then adding the new
document. | |||||||||||
Returns true if verbosing is enabled (i.e., infoStream != null).
| |||||||||||
Wait for any currently outstanding merges to finish.
|
Protected Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
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).
| |||||||||||
A hook for extending classes to execute operations before pending added and
deleted documents are flushed to the Directory.
| |||||||||||
Used internally to throw an
AlreadyClosedException if this IndexWriter has been
closed. | |||||||||||
Flush all in-memory buffered udpates (adds and deletes)
to the Directory.
|
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.lang.Object
| |||||||||||
From interface
java.io.Closeable
|
Disabled by default (because IndexWriter flushes by RAM usage
by default). Change using setMaxBufferedDeleteTerms(int)
.
Disabled by default (because IndexWriter flushes by RAM usage
by default). Change using setMaxBufferedDocs(int)
.
Default value is 10,000. Change using setMaxFieldLength(int)
.
Default value is 16 MB (which means flush when buffered
docs consume 16 MB RAM). Change using setRAMBufferSizeMB(double)
.
Default value is 128. Change using setTermIndexInterval(int)
.
Value to denote a flush trigger is disabled
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(PrintStream)
).
Name of the write lock in the index.
Default value for the write lock timeout (1,000).
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.
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. |
CorruptIndexException | if the index is corrupt |
---|---|
LockObtainFailedException | if another writer
has this index open (write.lock could not
be obtained) |
IOException | if the directory cannot be read/written to, or
if it does not exist and create is
false or if there is any other low-level
IO error
|
Constructs an IndexWriter for the index in
d
, first creating it if it does not
already exist. Text will be analyzed with
a
.
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. |
CorruptIndexException | if the index is corrupt |
---|---|
LockObtainFailedException | if another writer
has this index open (write.lock could not
be obtained) |
IOException | if the directory cannot be read/written to or if there is any other low-level IO error |
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
.
d | the index directory |
---|---|
a | the analyzer to use |
deletionPolicy | see above |
mfl | whether or not to limit field lengths |
CorruptIndexException | if the index is corrupt |
---|---|
LockObtainFailedException | if another writer
has this index open (write.lock could not
be obtained) |
IOException | if the directory cannot be read/written to or if there is any other low-level IO error |
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.
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 | IndexWriter.MaxFieldLength , whether or not to limit field lengths. Value is in number of terms/tokens |
CorruptIndexException | if the index is corrupt |
---|---|
LockObtainFailedException | if another writer
has this index open (write.lock could not
be obtained) |
IOException | if the directory cannot be read/written to, or
if it does not exist and create is
false or if there is any other low-level
IO error
|
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.
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 IndexWriter.MaxFieldLength . |
commit | which commit to open |
CorruptIndexException | if the index is corrupt |
---|---|
LockObtainFailedException | if another writer
has this index open (write.lock could not
be obtained) |
IOException | if the directory cannot be read/written to, or
if it does not exist and create is
false or if there is any other low-level
IO error
|
Adds a document to this index, using the provided analyzer instead of the
value of getAnalyzer()
. 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.
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
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.
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
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.
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
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.
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
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.
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
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.
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. |
---|
CorruptIndexException | |
---|---|
IOException |
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.
CorruptIndexException | |
---|---|
IOException |
Commits all changes to the index, specifying a
commitUserData Map (String -> String). This just
calls prepareCommit(Map)
(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.
CorruptIndexException | |
---|---|
IOException |
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 MergePolicy.MergeAbortedException
s.
IOException |
---|
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.
queries | array of queries to identify the documents to be deleted |
---|
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
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.
query | the query to identify the documents to be deleted |
---|
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
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.
terms | array of terms to identify the documents to be deleted |
---|
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
Deletes the document(s) containing term
.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
term | the term to identify the documents to be deleted |
---|
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
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.
CorruptIndexException | |
---|---|
IOException |
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
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 findMergesToExpungeDeletes(SegmentInfos)
.). Note that
this call does not first commit any buffered
documents, so you must do so yourself if necessary.
See also expungeDeletes(boolean)
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
CorruptIndexException | |
---|---|
IOException |
Returns the current default infoStream for newly instantiated IndexWriters.
Returns default write lock timeout for newly instantiated IndexWriters.
Returns the number of buffered deleted terms that will trigger a flush if enabled.
Returns the number of buffered added documents that will trigger a flush if enabled.
Returns the maximum number of terms that will be indexed for a single field in a document.
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 LogMergePolicy
.
Otherwise an IllegalArgumentException is thrown.
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 LogMergePolicy
.
Otherwise an IllegalArgumentException is thrown.
Expert: returns the current MergePolicy in use by this writer.
Expert: returns the current MergePolicy in use by this writer.
Returns the current merged segment warmer. See IndexWriter.IndexReaderWarmer
.
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 open(IndexCommit, boolean)
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 fast 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 supports 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 setMergedSegmentWarmer(IndexWriter.IndexReaderWarmer)
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.
IOException |
---|
Expert: like getReader()
, except you can
specify which termInfosIndexDivisor should be used for
any newly opened readers.
termInfosIndexDivisor | Subsamples which indexed
terms are loaded into RAM. This has the same effect as setTermIndexInterval(int) 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. |
---|
IOException |
---|
Expert: Return the Similarity implementation used by this IndexWriter.
This defaults to the current value of getDefault()
.
Expert: Return the interval between indexed terms.
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 LogMergePolicy
.
Otherwise an IllegalArgumentException is thrown.
Returns allowed timeout when acquiring the write lock.
Returns true
iff the index in the named directory is
currently locked.
directory | the directory to check for a lock |
---|
IOException | if there is a low-level IO error |
---|
Returns total number of docs in this index, including docs not yet flushed (still in the RAM buffer), not counting deletions.
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.
CorruptIndexException | |
---|---|
IOException |
Prints a message to the infoStream (if non-null), prefixed with the identifying information for this writer and the thread that's calling it.
Obtain the number of deleted docs for a pooled reader. If the reader isn't being pooled, the segmentInfo's delCount is returned.
IOException |
---|
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.
IOException |
---|
Expert: Return the number of documents currently buffered in RAM.
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.
maxNumSegments | maximum number of segments left in the index after optimization finishes |
---|
CorruptIndexException | |
---|---|
IOException |
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.
CorruptIndexException | |
---|---|
IOException |
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.
CorruptIndexException | |
---|---|
IOException |
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 individual 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.
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
Expert: prepare for commit, specifying
commitUserData Map (String -> String). This does the
first phase of 2-phase commit. This method does all
steps necessary to commit changes since this writer
was opened: flushes pending added and deleted docs,
syncs the index files, writes most of next segments_N
file. After calling this you must call either commit()
to finish the commit, or rollback()
to revert the commit and undo all changes
done since the writer was opened.
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.
commitUserData | Opaque Map (String->String)
that's recorded into the segments file in the index,
and retrievable by getCommitUserData() . Note that when
IndexWriter commits itself during close() , the
commitUserData is unchanged (just carried over from
the prior commit). If this is null then the previous
commitUserData is kept. Also, the commitUserData will
only "stick" if there are actually changes in the
index to commit.
|
---|
CorruptIndexException | |
---|---|
IOException |
Expert: prepare for commit.
NOTE: if this method hits an OutOfMemoryError you should immediately close the writer. See above for details.
CorruptIndexException | |
---|---|
IOException |
Expert: Return the total size of all index files currently cached in memory. Useful for size management with flushRamDocs()
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()
.
IOException | if there is a low-level IO error |
---|
If non-null, this will be the default infoStream used by a newly instantiated IndexWriter.
Sets the default (for any instance of IndexWriter) maximum time to wait for a write lock (in milliseconds).
If non-null, information about merges, deletes and a message when maxFieldLength is reached will be printed to this.
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).
IllegalArgumentException | if maxBufferedDeleteTerms is enabled but smaller than 1 |
---|
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).
IllegalArgumentException | if maxBufferedDocs is enabled but smaller than 2, or it disables maxBufferedDocs when ramBufferSize is already disabled |
---|
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 thanDEFAULT_MAX_FIELD_LENGTH
terms
will be indexed for a field.
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 MAX_VALUE
.
Note that this method is a convenience method: it
just calls mergePolicy.setMaxMergeDocs 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 setMaxMergeMB(double)
.
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.
Expert: set the merge scheduler used by this writer.
CorruptIndexException | |
---|---|
IOException |
Set the merged segment warmer. See IndexWriter.IndexReaderWarmer
.
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(int)
to flush by count
instead of RAM usage (each buffered delete Query counts
as one).
NOTE: because IndexWriter uses
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 DEFAULT_RAM_BUFFER_SIZE_MB
.
IllegalArgumentException | if ramBufferSize is enabled but non-positive, or it disables ramBufferSize when maxBufferedDocs is already disabled |
---|
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.
Expert: Set the Similarity implementation used by this IndexWriter.
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, numUniqueTerms/interval
terms are read into
memory by an IndexReader, and, on average, interval/2
terms
must be scanned for each random term access.
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 LogMergePolicy
.
Otherwise an IllegalArgumentException is thrown.
Sets the maximum time to wait for a write lock (in milliseconds) for this instance of IndexWriter. @see
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.
IOException |
---|
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.
term | the term to identify the document(s) to be deleted |
---|---|
doc | the document to be added |
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
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.
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 |
CorruptIndexException | if the index is corrupt |
---|---|
IOException | if there is a low-level IO error |
Returns true if verbosing is enabled (i.e., infoStream != null).
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.
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).
IOException |
---|
A hook for extending classes to execute operations before pending added and deleted documents are flushed to the Directory.
IOException |
---|
Used internally to throw an AlreadyClosedException
if this IndexWriter has been
closed.
AlreadyClosedException | if this IndexWriter is |
---|
Flush all in-memory buffered udpates (adds and deletes) to the Directory.
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 |
CorruptIndexException | |
---|---|
IOException |