org.apache.lucene.index
public class IndexWriter extends Object
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. 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 IndexWriter) or enough added documents (see IndexWriter) since the last flush, whichever is sooner. You can also force a flush by calling IndexWriter. When a flush occurs, both pending deletes and added documents are flushed to the index. A flush may also trigger one or more segment merges.
The optional autoCommit
argument to the
constructors
controls visibility of the changes to IndexReader instances reading the same index.
When this is false
, changes are not
visible until close is called.
Note that changes will still be flushed to the
Directory as new files,
but are not committed (no new segments_N
file
is written referencing the new files) until IndexWriter is
called. If something goes terribly wrong (for example the
JVM crashes) before close, then
the index will reflect none of the changes made (it will
remain in its starting state).
You can also call abort, which closes the writer without committing any
changes, and removes any index
files that had been flushed but are now unreferenced.
This mode is useful for preventing readers from refreshing
at a bad time (for example after you've done all your
deletes but before you've done your adds).
It can also be used to implement simple single-writer
transactional semantics ("all or none").
When autoCommit
is true
then
every flush is also a commit (IndexReader
instances will see each flush as changes to the index).
This is the default, to match the behavior before 2.2.
When running in this mode, be careful not to refresh your
readers while optimize or segment merges are taking place
as this can tie up substantial disk space.
Regardless of autoCommit
, an IndexReader or IndexSearcher will only see the
index as of the "point in time" that it was opened. Any
changes committed to the index after the reader was opened
are not visible until the reader is re-opened.
If an index will not have more documents added for a while and optimal search performance is desired, then the optimize 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.
Field Summary | |
---|---|
static int | DEFAULT_MAX_BUFFERED_DELETE_TERMS
Default value is 1000. |
static int | DEFAULT_MAX_BUFFERED_DOCS
Default value is 10. |
static int | DEFAULT_MAX_FIELD_LENGTH
Default value is 10,000. |
static int | DEFAULT_MAX_MERGE_DOCS
Default value is Integer#MAX_VALUE. |
static int | DEFAULT_MERGE_FACTOR
Default value is 10. |
static int | DEFAULT_TERM_INDEX_INTERVAL
Default value is 128. |
static String | WRITE_LOCK_NAME
Name of the write lock in the index. |
static long | WRITE_LOCK_TIMEOUT
Default value for the write lock timeout (1,000). |
Constructor Summary | |
---|---|
IndexWriter(String path, Analyzer a, boolean create)
Constructs an IndexWriter for the index in path .
| |
IndexWriter(File path, Analyzer a, boolean create)
Constructs an IndexWriter for the index in path .
| |
IndexWriter(Directory d, Analyzer a, boolean create)
Constructs an IndexWriter for the index in d .
| |
IndexWriter(String path, Analyzer a)
Constructs an IndexWriter for the index in
path , first creating it if it does not
already exist. | |
IndexWriter(File path, Analyzer a)
Constructs an IndexWriter for the index in
path , first creating it if it does not
already exist. | |
IndexWriter(Directory d, Analyzer a)
Constructs an IndexWriter for the index in
d , first creating it if it does not
already exist. | |
IndexWriter(Directory d, boolean autoCommit, Analyzer a)
Constructs an IndexWriter for the index in
d , first creating it if it does not
already exist. | |
IndexWriter(Directory d, boolean autoCommit, Analyzer a, boolean create)
Constructs an IndexWriter for the index in d .
| |
IndexWriter(Directory d, boolean autoCommit, Analyzer a, IndexDeletionPolicy deletionPolicy)
Expert: constructs an IndexWriter with a custom IndexDeletionPolicy, for the index in d ,
first creating it if it does not already exist. | |
IndexWriter(Directory d, boolean autoCommit, Analyzer a, boolean create, IndexDeletionPolicy deletionPolicy)
Expert: constructs an IndexWriter with a custom IndexDeletionPolicy, for the index in d .
|
Method Summary | |
---|---|
void | abort()
Close the IndexWriter without committing
any of the changes that have occurred since it was
opened. |
void | addDocument(Document doc)
Adds a document to this index. |
void | addDocument(Document doc, Analyzer analyzer)
Adds a document to this index, using the provided analyzer instead of the
value of getAnalyzer. |
void | addIndexes(Directory[] dirs) Merges all segments from an array of indexes into this index.
|
void | addIndexes(IndexReader[] readers) Merges the provided indexes into this index.
|
void | addIndexesNoOptimize(Directory[] dirs)
Merges all segments from an array of indexes into this index.
|
void | close()
Flushes all changes to an index and closes all
associated files.
|
void | deleteDocuments(Term term)
Deletes the document(s) containing term . |
void | deleteDocuments(Term[] terms)
Deletes the document(s) containing any of the
terms. |
int | docCount() Returns the number of documents currently in this index. |
protected void | ensureOpen()
Used internally to throw an AlreadyClosedException if this IndexWriter has been
closed. |
protected void | finalize() Release the write lock, if needed. |
void | flush()
Flush all in-memory buffered updates (adds and deletes)
to the Directory.
|
protected void | flushRamSegments(boolean triggerMerge) Expert: Flushes all RAM-resident segments (buffered documents),
then may merge segments if triggerMerge==true. |
Analyzer | getAnalyzer() Returns the analyzer used by this index. |
static PrintStream | getDefaultInfoStream()
Returns the current default infoStream for newly
instantiated IndexWriters. |
static long | getDefaultWriteLockTimeout()
Returns default write lock timeout for newly
instantiated IndexWriters. |
Directory | getDirectory() Returns the Directory used by this index. |
PrintStream | getInfoStream()
Returns the current infoStream in use by this writer. |
int | getMaxBufferedDeleteTerms()
Returns the number of buffered deleted terms that will
trigger a flush. |
int | getMaxBufferedDocs()
Returns the number of buffered added documents that will
trigger a flush. |
int | getMaxFieldLength()
Returns the maximum number of terms that will be
indexed for a single field in a document. |
int | getMaxMergeDocs()
Returns the largest number of documents allowed in a
single segment. |
int | getMergeFactor()
Returns the number of segments that are merged at once
and also controls the total number of segments allowed
to accumulate in the index. |
Similarity | getSimilarity() Expert: Return the Similarity implementation used by this IndexWriter.
|
int | getTermIndexInterval() Expert: Return the interval between indexed terms.
|
boolean | getUseCompoundFile() Get the current setting of whether to use the compound file format.
|
long | getWriteLockTimeout()
Returns allowed timeout when acquiring the write lock. |
protected void | maybeFlushRamSegments()
Used internally to trigger a flush if the number of
buffered added documents or buffered deleted terms are
large enough. |
int | numRamDocs() Expert: Return the number of documents whose segments are currently cached in memory.
|
void | optimize() Merges all segments together into a single segment,
optimizing an index for search.
|
long | ramSizeInBytes() Expert: Return the total size of all index files currently cached in memory.
|
static void | setDefaultInfoStream(PrintStream infoStream) If non-null, this will be the default infoStream used
by a newly instantiated IndexWriter. |
static void | setDefaultWriteLockTimeout(long writeLockTimeout)
Sets the default (for any instance of IndexWriter) maximum time to wait for a write lock (in
milliseconds). |
void | setInfoStream(PrintStream infoStream) If non-null, information about merges, deletes and a
message when maxFieldLength is reached will be printed
to this. |
void | setMaxBufferedDeleteTerms(int maxBufferedDeleteTerms) Determines the minimal number of delete terms required before the buffered in-memory delete terms are applied and flushed. |
void | setMaxBufferedDocs(int maxBufferedDocs) Determines the minimal number of documents required before the buffered
in-memory documents are merged and a new Segment is created.
|
void | setMaxFieldLength(int maxFieldLength)
The maximum number of terms that will be indexed for a single field in a
document. |
void | setMaxMergeDocs(int maxMergeDocs) Determines the largest number of documents ever merged by addDocument().
|
void | setMergeFactor(int mergeFactor) Determines how often segment indices are merged by addDocument(). |
void | setSimilarity(Similarity similarity) Expert: Set the Similarity implementation used by this IndexWriter.
|
void | setTermIndexInterval(int interval) Expert: Set the interval between indexed terms. |
void | setUseCompoundFile(boolean value) Setting to turn on usage of a compound file. |
void | setWriteLockTimeout(long writeLockTimeout)
Sets the maximum time to wait for a write lock (in milliseconds) for this instance of IndexWriter. |
void | updateDocument(Term term, Document doc)
Updates a document by first deleting the document(s)
containing term and then adding the new
document. |
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. |
See Also: IndexWriter
path
.
Text will be analyzed with a
. If create
is true, then a new, empty index will be created in
path
, replacing the index already there, if any.
Parameters: path the path to 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
Throws: 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
path
.
Text will be analyzed with a
. If create
is true, then a new, empty index will be created in
path
, replacing the index already there, if any.
Parameters: path the path to 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
Throws: 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
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
Throws: 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
path
, first creating it if it does not
already exist. Text will be analyzed with
a
.
Parameters: path the path to the index directory a the analyzer to use
Throws: 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
path
, first creating it if it does not
already exist. Text will be analyzed with
a
.
Parameters: path the path to the index directory a the analyzer to use
Throws: 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
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
Throws: 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
d
, first creating it if it does not
already exist. Text will be analyzed with
a
.
Parameters: d the index directory autoCommit see above a the analyzer to use
Throws: 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
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 autoCommit see above a the analyzer to use create true
to create the index or overwrite
the existing one; false
to append to the existing
index
Throws: 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
d
,
first creating it if it does not already exist. Text
will be analyzed with a
.
Parameters: d the index directory autoCommit see above a the analyzer to use deletionPolicy see above
Throws: 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
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 autoCommit see above 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
Throws: 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
IndexWriter
without committing
any of the changes that have occurred since it was
opened. This removes any temporary files that had been
created, after which the state of the index will be the
same as it was when this writer was first opened. This
can only be called when this IndexWriter was opened
with autoCommit=false
.Throws: IllegalStateException if this is called when
the writer was opened with autoCommit=true
. IOException if there is a low-level IO error
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 (every IndexWriter), and also periodically merges segments in the index (every IndexWriter flushes). When this occurs, the method will take more time to run (possibly a long time if the index is large), and will require free temporary space in the Directory to do the merging.
The amount of free space required when a merge is triggered 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). Most merges are small (merging the smallest segments together), but whenever a full merge occurs (all segments in the index, which is the worst case for temporary space usage) then the maximum free disk space required is the same as IndexWriter.
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
See addDocument for details on index and IndexWriter state after an Exception, and flushing/merging temporary free space requirements.
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
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.
After this completes, the index is optimized.
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.
If an Exception is hit, it's still possible that all indexes were successfully added. This happens when the Exception is hit when trying to build a CFS file. In this case, one segment in the index will be in non-CFS format, even when using compound file format.
Also note that on an Exception, the index may still have been partially or fully optimized even though none of the input indexes were added.
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.
See LUCENE-702 for details.
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
After this completes, the index is optimized.
The provided IndexReaders are not closed.
See (Directory[])
for
details on transactional semantics, temporary free
space required in the Directory, and non-CFS segments
on an Exception.
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
This is similar to addIndexes(Directory[]). However, no optimize() is called either at the beginning or at the end. Instead, merges are carried out as necessary.
This requires this index not be among those to be added, and the upper bound* of those segment doc counts not exceed maxMergeDocs.
See (Directory[])
for
details on transactional semantics, temporary free
space required in the Directory, and non-CFS segments
on an Exception.
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
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 (IndexReader.isLocked(directory)) { IndexReader.unlock(directory); } }after which, you must be certain not to use the writer instance anymore.
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
term
.Parameters: term the term to identify the documents to be deleted
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
Parameters: terms array of terms to identify the documents to be deleted
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
Throws: AlreadyClosedException if this IndexWriter is
Note: if autoCommit=false
, flushed data would still
not be visible to readers, until IndexWriter is called.
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
See Also: IndexWriter
See Also: IndexWriter
See Also: IndexWriter
See Also: IndexWriter
See Also: IndexWriter
See Also: IndexWriter
See Also: IndexWriter
See Also: IndexWriter
This defaults to the current value of getDefault.
See Also: IndexWriter
See Also: IndexWriter
See Also: IndexWriter
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 this requires substantial temporary free space in the Directory (see LUCENE-764 for details):
If no readers/searchers are open against the index, then free space required is up to 1X the total size of the starting index. For example, if the starting index is 10 GB, then you must have up to 10 GB of free space before calling optimize.
If readers/searchers are using the index, then free space required is up to 2X the size of the starting index. This is because in addition to the 1X used by optimize, the original 1X of the starting index is still consuming space in the Directory as the readers are holding the segments files open. Even on Unix, where it will appear as if the files are gone ("ls" won't list them), they still consume storage due to "delete on last close" semantics.
Furthermore, if some but not all readers re-open while the 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).
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.
Throws: CorruptIndexException if the index is corrupt IOException if there is a low-level IO error
See Also: IndexWriter
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.
The default value is DEFAULT_MAX_BUFFERED_DELETE_TERMS.
Throws: IllegalArgumentException if maxBufferedDeleteTerms is smaller than 1
The default value is 10.
Throws: IllegalArgumentException if maxBufferedDocs is smaller than 2
The default value is Integer#MAX_VALUE.
This must never be less than 2. The default value is 10.
See Also: setDefault
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
See Also: to change the default value for all instances of IndexWriter.
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).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 IOException if there is a low-level IO error
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).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 IOException if there is a low-level IO error