Class IndexReader
- java.lang.Object
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- org.apache.lucene.index.IndexReader
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- All Implemented Interfaces:
Closeable
,AutoCloseable
,Cloneable
- Direct Known Subclasses:
FilterIndexReader
,MultiReader
,ParallelReader
,SegmentReader
public abstract class IndexReader extends Object implements Cloneable, Closeable
IndexReader is an abstract class, providing an interface for accessing an index. Search of an index is done entirely through this abstract interface, so that any subclass which implements it is searchable.Concrete subclasses of IndexReader are usually constructed with a call to one of the static
open()
methods, e.g.open(Directory, boolean)
.For efficiency, in this API documents are often referred to via document numbers, non-negative integers which each name a unique document in the index. These document numbers are ephemeral--they may change as documents are added to and deleted from an index. Clients should thus not rely on a given document having the same number between sessions.
An IndexReader can be opened on a directory for which an IndexWriter is opened already, but it cannot be used to delete documents from the index then.
NOTE: for backwards API compatibility, several methods are not listed as abstract, but have no useful implementations in this base class and instead always throw UnsupportedOperationException. Subclasses are strongly encouraged to override these methods, but in many cases may not need to.
NOTE: as of 2.4, it's possible to open a read-only IndexReader using the static open methods that accept the boolean readOnly parameter. Such a reader has better concurrency as it's not necessary to synchronize on the isDeleted method. You must specify false if you want to make changes with the resulting IndexReader.
NOTE:
IndexReader
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 theIndexReader
instance; use your own (non-Lucene) objects instead.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static interface
IndexReader.ReaderClosedListener
A custom listener that's invoked when the IndexReader is closed.
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Field Summary
Fields Modifier and Type Field Description protected boolean
hasChanges
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Constructor Summary
Constructors Modifier Constructor Description protected
IndexReader()
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods Modifier and Type Method Description protected void
acquireWriteLock()
Deprecated.Write support will be removed in Lucene 4.0.void
addReaderClosedListener(IndexReader.ReaderClosedListener listener)
Expert: adds aIndexReader.ReaderClosedListener
.Object
clone()
Efficiently clones the IndexReader (sharing most internal state).IndexReader
clone(boolean openReadOnly)
Deprecated.Write support will be removed in Lucene 4.0.void
close()
Closes files associated with this index.protected void
commit()
Deprecated.Write support will be removed in Lucene 4.0.void
commit(Map<String,String> commitUserData)
Deprecated.Write support will be removed in Lucene 4.0.void
decRef()
Expert: decreases the refCount of this IndexReader instance.void
deleteDocument(int docNum)
Deprecated.Write support will be removed in Lucene 4.0.int
deleteDocuments(Term term)
Deprecated.Write support will be removed in Lucene 4.0.Directory
directory()
Returns the directory associated with this index.abstract int
docFreq(Term t)
Returns the number of documents containing the termt
.protected abstract void
doClose()
Implements close.protected abstract void
doCommit(Map<String,String> commitUserData)
Deprecated.Write support will be removed in Lucene 4.0.Document
document(int n)
Returns the stored fields of then
thDocument
in this index.abstract Document
document(int n, FieldSelector fieldSelector)
Get theDocument
at then
th position.protected abstract void
doDelete(int docNum)
Deprecated.Write support will be removed in Lucene 4.0.protected IndexReader
doOpenIfChanged()
If the index has changed since it was opened, open and return a new reader; else, returnnull
.protected IndexReader
doOpenIfChanged(boolean openReadOnly)
Deprecated.Write support will be removed in Lucene 4.0.protected IndexReader
doOpenIfChanged(IndexCommit commit)
If the index has changed since it was opened, open and return a new reader; else, returnnull
.protected IndexReader
doOpenIfChanged(IndexWriter writer, boolean applyAllDeletes)
If the index has changed since it was opened, open and return a new reader; else, returnnull
.protected abstract void
doSetNorm(int doc, String field, byte value)
Deprecated.Write support will be removed in Lucene 4.0.protected abstract void
doUndeleteAll()
Deprecated.Write support will be removed in Lucene 4.0.protected void
ensureOpen()
void
flush()
Deprecated.Write support will be removed in Lucene 4.0.void
flush(Map<String,String> commitUserData)
Deprecated.Write support will be removed in Lucene 4.0.Map<String,String>
getCommitUserData()
Deprecated.CallgetIndexCommit()
and then callIndexCommit.getUserData()
.static Map<String,String>
getCommitUserData(Directory directory)
Deprecated.CallgetIndexCommit()
on an open IndexReader, and then callIndexCommit.getUserData()
.Object
getCoreCacheKey()
Expertstatic long
getCurrentVersion(Directory directory)
Deprecated.UsegetVersion()
on an opened IndexReader.Object
getDeletesCacheKey()
Expert.abstract FieldInfos
getFieldInfos()
Get theFieldInfos
describing all fields in this reader.IndexCommit
getIndexCommit()
Expert: return the IndexCommit that this reader has opened.int
getRefCount()
Expert: returns the current refCount for this readerIndexReader[]
getSequentialSubReaders()
Expert: returns the sequential sub readers that this reader is logically composed of.abstract TermFreqVector
getTermFreqVector(int docNumber, String field)
Return a term frequency vector for the specified document and field.abstract void
getTermFreqVector(int docNumber, String field, TermVectorMapper mapper)
Load the Term Vector into a user-defined data structure instead of relying on the parallel arrays of theTermFreqVector
.abstract void
getTermFreqVector(int docNumber, TermVectorMapper mapper)
Map all the term vectors for all fields in a Documentabstract TermFreqVector[]
getTermFreqVectors(int docNumber)
Return an array of term frequency vectors for the specified document.int
getTermInfosIndexDivisor()
For IndexReader implementations that use TermInfosReader to read terms, this returns the current indexDivisor as specified when the reader was opened.long
getUniqueTermCount()
Returns the number of unique terms (across all fields) in this reader.long
getVersion()
Version number when this IndexReader was opened.abstract boolean
hasDeletions()
Returns true if any documents have been deletedboolean
hasNorms(String field)
Returns true if there are norms stored for this field.void
incRef()
Expert: increments the refCount of this IndexReader instance.static boolean
indexExists(Directory directory)
Returnstrue
if an index exists at the specified directory.boolean
isCurrent()
Check whether any new changes have occurred to the index since this reader was opened.abstract boolean
isDeleted(int n)
Returns true if document n has been deletedboolean
isOptimized()
Deprecated.Check segment count usinggetSequentialSubReaders()
instead.static long
lastModified(Directory directory2)
Deprecated.If you need to track commit time of an index, you can store it in the commit data (seeIndexWriter.commit(Map)
static Collection<IndexCommit>
listCommits(Directory dir)
Returns all commit points that exist in the Directory.abstract int
maxDoc()
Returns one greater than the largest possible document number.abstract byte[]
norms(String field)
Returns the byte-encoded normalization factor for the named field of every document.abstract void
norms(String field, byte[] bytes, int offset)
Reads the byte-encoded normalization factor for the named field of every document.int
numDeletedDocs()
Returns the number of deleted documents.abstract int
numDocs()
Returns the number of documents in this index.static IndexReader
open(IndexCommit commit)
Expert: returns an IndexReader reading the index in the givenIndexCommit
.static IndexReader
open(IndexCommit commit, boolean readOnly)
Deprecated.Write support will be removed in Lucene 4.0.static IndexReader
open(IndexCommit commit, int termInfosIndexDivisor)
Expert: returns an IndexReader reading the index in the givenIndexCommit
and termInfosIndexDivisor.static IndexReader
open(IndexCommit commit, IndexDeletionPolicy deletionPolicy, boolean readOnly)
Deprecated.Write support will be removed in Lucene 4.0.static IndexReader
open(IndexCommit commit, IndexDeletionPolicy deletionPolicy, boolean readOnly, int termInfosIndexDivisor)
Deprecated.Write support will be removed in Lucene 4.0.static IndexReader
open(IndexWriter writer, boolean applyAllDeletes)
Open a near real time IndexReader from theIndexWriter
.static IndexReader
open(Directory directory)
Returns a IndexReader reading the index in the given Directory, with readOnly=true.static IndexReader
open(Directory directory, boolean readOnly)
Deprecated.Write support will be removed in Lucene 4.0.static IndexReader
open(Directory directory, int termInfosIndexDivisor)
Expert: Returns a IndexReader reading the index in the given Director and given termInfosIndexDivisorstatic IndexReader
open(Directory directory, IndexDeletionPolicy deletionPolicy, boolean readOnly)
Deprecated.Write support will be removed in Lucene 4.0.static IndexReader
open(Directory directory, IndexDeletionPolicy deletionPolicy, boolean readOnly, int termInfosIndexDivisor)
Deprecated.Write support will be removed in Lucene 4.0.static IndexReader
openIfChanged(IndexReader oldReader)
If the index has changed since the provided reader was opened, open and return a new reader; else, return null.static IndexReader
openIfChanged(IndexReader oldReader, boolean readOnly)
Deprecated.Write support will be removed in Lucene 4.0.static IndexReader
openIfChanged(IndexReader oldReader, IndexCommit commit)
If the IndexCommit differs from what the provided reader is searching, or the provided reader is not already read-only, open and return a newreadOnly=true
reader; else, return null.static IndexReader
openIfChanged(IndexReader oldReader, IndexWriter writer, boolean applyAllDeletes)
Expert: If there changes (committed or not) in theIndexWriter
versus what the provided reader is searching, then open and return a new read-only IndexReader searching both committed and uncommitted changes from the writer; else, return null (though, the current implementation never returns null).void
removeReaderClosedListener(IndexReader.ReaderClosedListener listener)
Expert: remove a previously addedIndexReader.ReaderClosedListener
.IndexReader
reopen()
Deprecated.UseopenIfChanged(IndexReader)
insteadIndexReader
reopen(boolean openReadOnly)
Deprecated.Write support will be removed in Lucene 4.0.IndexReader
reopen(IndexCommit commit)
Deprecated.UseopenIfChanged(IndexReader,IndexCommit)
insteadIndexReader
reopen(IndexWriter writer, boolean applyAllDeletes)
Deprecated.UseopenIfChanged(IndexReader,IndexWriter,boolean)
insteadvoid
setNorm(int doc, String field, byte value)
Deprecated.Write support will be removed in Lucene 4.0.void
setNorm(int doc, String field, float value)
Deprecated.Write support will be removed in Lucene 4.0.abstract TermDocs
termDocs()
Returns an unpositionedTermDocs
enumerator.TermDocs
termDocs(Term term)
Returns an enumeration of all the documents which containterm
.abstract TermPositions
termPositions()
Returns an unpositionedTermPositions
enumerator.TermPositions
termPositions(Term term)
Returns an enumeration of all the documents which containterm
.abstract TermEnum
terms()
Returns an enumeration of all the terms in the index.abstract TermEnum
terms(Term t)
Returns an enumeration of all terms starting at a given term.String
toString()
boolean
tryIncRef()
Expert: increments the refCount of this IndexReader instance only if the IndexReader has not been closed yet and returnstrue
iff the refCount was successfully incremented, otherwisefalse
.void
undeleteAll()
Deprecated.Write support will be removed in Lucene 4.0.
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Method Detail
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addReaderClosedListener
public final void addReaderClosedListener(IndexReader.ReaderClosedListener listener)
Expert: adds aIndexReader.ReaderClosedListener
. The provided listener will be invoked when this reader is closed.- WARNING: This API is experimental and might change in incompatible ways in the next release.
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removeReaderClosedListener
public final void removeReaderClosedListener(IndexReader.ReaderClosedListener listener)
Expert: remove a previously addedIndexReader.ReaderClosedListener
.- WARNING: This API is experimental and might change in incompatible ways in the next release.
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getRefCount
public final int getRefCount()
Expert: returns the current refCount for this reader
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incRef
public final void incRef()
Expert: increments the refCount of this IndexReader instance. RefCounts are used to determine when a reader can be closed safely, i.e. as soon as there are no more references. Be sure to always call a correspondingdecRef()
, in a finally clause; otherwise the reader may never be closed. Note thatclose()
simply calls decRef(), which means that the IndexReader will not really be closed untildecRef()
has been called for all outstanding references.- See Also:
decRef()
,tryIncRef()
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tryIncRef
public final boolean tryIncRef()
Expert: increments the refCount of this IndexReader instance only if the IndexReader has not been closed yet and returnstrue
iff the refCount was successfully incremented, otherwisefalse
. If this method returnsfalse
the reader is either already closed or is currently been closed. Either way this reader instance shouldn't be used by an application unlesstrue
is returned.RefCounts are used to determine when a reader can be closed safely, i.e. as soon as there are no more references. Be sure to always call a corresponding
decRef()
, in a finally clause; otherwise the reader may never be closed. Note thatclose()
simply calls decRef(), which means that the IndexReader will not really be closed untildecRef()
has been called for all outstanding references.
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decRef
public final void decRef() throws IOException
Expert: decreases the refCount of this IndexReader instance. If the refCount drops to 0, then pending changes (if any) are committed to the index and this reader is closed. If an exception is hit, the refCount is unchanged.- Throws:
IOException
- in case an IOException occurs in commit() or doClose()- See Also:
incRef()
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ensureOpen
protected final void ensureOpen() throws AlreadyClosedException
- Throws:
AlreadyClosedException
- if this IndexReader is closed
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open
public static IndexReader open(Directory directory) throws CorruptIndexException, IOException
Returns a IndexReader reading the index in the given Directory, with readOnly=true.- Parameters:
directory
- the index directory- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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open
@Deprecated public static IndexReader open(Directory directory, boolean readOnly) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. Useopen(Directory)
insteadReturns an IndexReader reading the index in the given Directory. You should pass readOnly=true, since it gives much better concurrent performance, unless you intend to do write operations (delete documents or change norms) with the reader.- Parameters:
directory
- the index directoryreadOnly
- true if no changes (deletions, norms) will be made with this IndexReader- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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open
public static IndexReader open(IndexWriter writer, boolean applyAllDeletes) throws CorruptIndexException, IOException
Open a near real time IndexReader from theIndexWriter
.- Parameters:
writer
- The IndexWriter to open fromapplyAllDeletes
- If true, all buffered deletes will be applied (made visible) in the returned reader. If false, the deletes are not applied but remain buffered (in IndexWriter) so that they will be applied in the future. Applying deletes can be costly, so if your app can tolerate deleted documents being returned you might gain some performance by passing false.- Returns:
- The new IndexReader
- Throws:
CorruptIndexException
IOException
- if there is a low-level IO error- See Also:
openIfChanged(IndexReader,IndexWriter,boolean)
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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open
public static IndexReader open(IndexCommit commit) throws CorruptIndexException, IOException
Expert: returns an IndexReader reading the index in the givenIndexCommit
.- Parameters:
commit
- the commit point to open- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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open
@Deprecated public static IndexReader open(IndexCommit commit, boolean readOnly) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. Useopen(IndexCommit)
insteadExpert: returns an IndexReader reading the index in the givenIndexCommit
. You should pass readOnly=true, since it gives much better concurrent performance, unless you intend to do write operations (delete documents or change norms) with the reader.- Parameters:
commit
- the commit point to openreadOnly
- true if no changes (deletions, norms) will be made with this IndexReader- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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open
@Deprecated public static IndexReader open(Directory directory, IndexDeletionPolicy deletionPolicy, boolean readOnly) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. Useopen(Directory)
insteadExpert: returns an IndexReader reading the index in the given Directory, with a customIndexDeletionPolicy
. You should pass readOnly=true, since it gives much better concurrent performance, unless you intend to do write operations (delete documents or change norms) with the reader.- Parameters:
directory
- the index directorydeletionPolicy
- a custom deletion policy (only used if you use this reader to perform deletes or to set norms); seeIndexWriter
for details.readOnly
- true if no changes (deletions, norms) will be made with this IndexReader- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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open
@Deprecated public static IndexReader open(Directory directory, IndexDeletionPolicy deletionPolicy, boolean readOnly, int termInfosIndexDivisor) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. Useopen(Directory,int)
insteadExpert: returns an IndexReader reading the index in the given Directory, with a customIndexDeletionPolicy
. You should pass readOnly=true, since it gives much better concurrent performance, unless you intend to do write operations (delete documents or change norms) with the reader.- Parameters:
directory
- the index directorydeletionPolicy
- a custom deletion policy (only used if you use this reader to perform deletes or to set norms); seeIndexWriter
for details.readOnly
- true if no changes (deletions, norms) will be made with this IndexReadertermInfosIndexDivisor
- Subsamples which indexed terms are loaded into RAM. This has the same effect asIndexWriter.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.- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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open
@Deprecated public static IndexReader open(IndexCommit commit, IndexDeletionPolicy deletionPolicy, boolean readOnly) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. Useopen(IndexCommit)
insteadExpert: returns an IndexReader reading the index in the given Directory, using a specific commit and with a customIndexDeletionPolicy
. You should pass readOnly=true, since it gives much better concurrent performance, unless you intend to do write operations (delete documents or change norms) with the reader.- Parameters:
commit
- the specificIndexCommit
to open; seelistCommits(org.apache.lucene.store.Directory)
to list all commits in a directorydeletionPolicy
- a custom deletion policy (only used if you use this reader to perform deletes or to set norms); seeIndexWriter
for details.readOnly
- true if no changes (deletions, norms) will be made with this IndexReader- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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open
@Deprecated public static IndexReader open(IndexCommit commit, IndexDeletionPolicy deletionPolicy, boolean readOnly, int termInfosIndexDivisor) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. Useopen(IndexCommit,int)
insteadExpert: returns an IndexReader reading the index in the given Directory, using a specific commit and with a customIndexDeletionPolicy
. You should pass readOnly=true, since it gives much better concurrent performance, unless you intend to do write operations (delete documents or change norms) with the reader.- Parameters:
commit
- the specificIndexCommit
to open; seelistCommits(org.apache.lucene.store.Directory)
to list all commits in a directorydeletionPolicy
- a custom deletion policy (only used if you use this reader to perform deletes or to set norms); seeIndexWriter
for details.readOnly
- true if no changes (deletions, norms) will be made with this IndexReadertermInfosIndexDivisor
- Subsamples which indexed terms are loaded into RAM. This has the same effect asIndexWriter.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. This is only useful in advanced situations when you will only .next() through all terms; attempts to seek will hit an exception.- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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open
public static IndexReader open(Directory directory, int termInfosIndexDivisor) throws CorruptIndexException, IOException
Expert: Returns a IndexReader reading the index in the given Director and given termInfosIndexDivisor- Parameters:
directory
- the index directorytermInfosIndexDivisor
- Subsamples which indexed terms are loaded into RAM. This has the same effect asIndexWriterConfig.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.- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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open
public static IndexReader open(IndexCommit commit, int termInfosIndexDivisor) throws CorruptIndexException, IOException
Expert: returns an IndexReader reading the index in the givenIndexCommit
and termInfosIndexDivisor.- Parameters:
commit
- the commit point to opentermInfosIndexDivisor
- Subsamples which indexed terms are loaded into RAM. This has the same effect asIndexWriterConfig.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.- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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openIfChanged
public static IndexReader openIfChanged(IndexReader oldReader) throws IOException
If the index has changed since the provided reader was opened, open and return a new reader; else, return null. The new reader, if not null, will be the same type of reader as the previous one, ie an NRT reader will open a new NRT reader, a MultiReader will open a new MultiReader, etc.This method is typically far less costly than opening a fully new
IndexReader
as it shares resources (for example sub-readers) with the providedIndexReader
, when possible.The provided reader is not closed (you are responsible for doing so); if a new reader is returned you also must eventually close it. Be sure to never close a reader while other threads are still using it; see
SearcherManager
to simplify managing this.If a new reader is returned, it's safe to make changes (deletions, norms) with it. All shared mutable state with the old reader uses "copy on write" semantics to ensure the changes are not seen by other readers.
- Returns:
- null if there are no changes; else, a new IndexReader instance which you must eventually close
- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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openIfChanged
@Deprecated public static IndexReader openIfChanged(IndexReader oldReader, boolean readOnly) throws IOException
Deprecated.Write support will be removed in Lucene 4.0. UseopenIfChanged(IndexReader)
insteadIf the index has changed since the provided reader was opened, open and return a new reader, with the specifiedreadOnly
; else, return null.- Throws:
IOException
- See Also:
openIfChanged(IndexReader)
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openIfChanged
public static IndexReader openIfChanged(IndexReader oldReader, IndexCommit commit) throws IOException
If the IndexCommit differs from what the provided reader is searching, or the provided reader is not already read-only, open and return a newreadOnly=true
reader; else, return null.- Throws:
IOException
- See Also:
openIfChanged(IndexReader)
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openIfChanged
public static IndexReader openIfChanged(IndexReader oldReader, IndexWriter writer, boolean applyAllDeletes) throws IOException
Expert: If there changes (committed or not) in theIndexWriter
versus what the provided reader is searching, then open and return a new read-only IndexReader searching both committed and uncommitted changes from the writer; else, return null (though, the current implementation never returns null).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 callingIndexWriter.commit()
.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 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
IndexWriterConfig.setMergedSegmentWarmer(org.apache.lucene.index.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
.- Parameters:
writer
- The IndexWriter to open fromapplyAllDeletes
- If true, all buffered deletes will be applied (made visible) in the returned reader. If false, the deletes are not applied but remain buffered (in IndexWriter) so that they will be applied in the future. Applying deletes can be costly, so if your app can tolerate deleted documents being returned you might gain some performance by passing false.- Returns:
- IndexReader that covers entire index plus all changes made so far by this IndexWriter instance, or null if there are no new changes
- Throws:
IOException
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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reopen
@Deprecated public IndexReader reopen() throws CorruptIndexException, IOException
Deprecated.UseopenIfChanged(IndexReader)
insteadRefreshes an IndexReader if the index has changed since this instance was (re)opened.Opening an IndexReader is an expensive operation. This method can be used to refresh an existing IndexReader to reduce these costs. This method tries to only load segments that have changed or were created after the IndexReader was (re)opened.
If the index has not changed since this instance was (re)opened, then this call is a NOOP and returns this instance. Otherwise, a new instance is returned. The old instance is not closed and remains usable.
If the reader is reopened, even though they share resources internally, it's safe to make changes (deletions, norms) with the new reader. All shared mutable state obeys "copy on write" semantics to ensure the changes are not seen by other readers.
You can determine whether a reader was actually reopened by comparing the old instance with the instance returned by this method:
IndexReader reader = ... ... IndexReader newReader = r.reopen(); if (newReader != reader) { ... // reader was reopened reader.close(); } reader = newReader; ...
Be sure to synchronize that code so that other threads, if present, can never use reader after it has been closed and before it's switched to newReader.NOTE: If this reader is a near real-time reader (obtained from
IndexWriter.getReader()
, reopen() will simply call writer.getReader() again for you, though this may change in the future.- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
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reopen
@Deprecated public IndexReader reopen(boolean openReadOnly) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. UseopenIfChanged(IndexReader)
insteadJust likereopen()
, except you can change the readOnly of the original reader. If the index is unchanged but readOnly is different then a new reader will be returned.- Throws:
CorruptIndexException
IOException
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reopen
@Deprecated public IndexReader reopen(IndexCommit commit) throws CorruptIndexException, IOException
Deprecated.UseopenIfChanged(IndexReader,IndexCommit)
insteadExpert: reopen this reader on a specific commit point. This always returns a readOnly reader. If the specified commit point matches what this reader is already on, and this reader is already readOnly, then this same instance is returned; if it is not already readOnly, a readOnly clone is returned.- Throws:
CorruptIndexException
IOException
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reopen
@Deprecated public IndexReader reopen(IndexWriter writer, boolean applyAllDeletes) throws CorruptIndexException, IOException
Deprecated.UseopenIfChanged(IndexReader,IndexWriter,boolean)
insteadExpert: 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 callingcommit()
.Note that this is functionally equivalent to calling {#flush} (an internal IndexWriter operation) and then using
open(org.apache.lucene.store.Directory)
to open a new reader. But the turnaround time of this method should be faster since it avoids the potentially costlycommit()
.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
IndexWriterConfig.setMergedSegmentWarmer(org.apache.lucene.index.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
.- Parameters:
writer
- The IndexWriter to open fromapplyAllDeletes
- If true, all buffered deletes will be applied (made visible) in the returned reader. If false, the deletes are not applied but remain buffered (in IndexWriter) so that they will be applied in the future. Applying deletes can be costly, so if your app can tolerate deleted documents being returned you might gain some performance by passing false.- Returns:
- IndexReader that covers entire index plus all changes made so far by this IndexWriter instance
- Throws:
IOException
CorruptIndexException
- WARNING: This API is experimental and might change in incompatible ways in the next release.
-
doOpenIfChanged
protected IndexReader doOpenIfChanged() throws CorruptIndexException, IOException
If the index has changed since it was opened, open and return a new reader; else, returnnull
.- Throws:
CorruptIndexException
IOException
- See Also:
openIfChanged(IndexReader)
-
doOpenIfChanged
@Deprecated protected IndexReader doOpenIfChanged(boolean openReadOnly) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. UsedoOpenIfChanged()
insteadIf the index has changed since it was opened, open and return a new reader; else, returnnull
.- Throws:
CorruptIndexException
IOException
- See Also:
openIfChanged(IndexReader, boolean)
-
doOpenIfChanged
protected IndexReader doOpenIfChanged(IndexCommit commit) throws CorruptIndexException, IOException
If the index has changed since it was opened, open and return a new reader; else, returnnull
.- Throws:
CorruptIndexException
IOException
- See Also:
openIfChanged(IndexReader, IndexCommit)
-
doOpenIfChanged
protected IndexReader doOpenIfChanged(IndexWriter writer, boolean applyAllDeletes) throws CorruptIndexException, IOException
If the index has changed since it was opened, open and return a new reader; else, returnnull
.- Throws:
CorruptIndexException
IOException
- See Also:
openIfChanged(IndexReader, IndexWriter, boolean)
-
clone
public Object clone()
Efficiently clones the IndexReader (sharing most internal state).On cloning a reader with pending changes (deletions, norms), the original reader transfers its write lock to the cloned reader. This means only the cloned reader may make further changes to the index, and commit the changes to the index on close, but the old reader still reflects all changes made up until it was cloned.
Like
openIfChanged(IndexReader)
, it's safe to make changes to either the original or the cloned reader: all shared mutable state obeys "copy on write" semantics to ensure the changes are not seen by other readers.
-
clone
@Deprecated public IndexReader clone(boolean openReadOnly) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. Useclone()
instead.Clones the IndexReader and optionally changes readOnly. A readOnly reader cannot open a writeable reader.- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
-
directory
public Directory directory()
Returns the directory associated with this index. The Default implementation returns the directory specified by subclasses when delegating to the IndexReader(Directory) constructor, or throws an UnsupportedOperationException if one was not specified.- Throws:
UnsupportedOperationException
- if no directory
-
lastModified
@Deprecated public static long lastModified(Directory directory2) throws CorruptIndexException, IOException
Deprecated.If you need to track commit time of an index, you can store it in the commit data (seeIndexWriter.commit(Map)
Returns the time the index in the named directory was last modified. Do not use this to check whether the reader is still up-to-date, useisCurrent()
instead.- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
-
getCurrentVersion
@Deprecated public static long getCurrentVersion(Directory directory) throws CorruptIndexException, IOException
Deprecated.UsegetVersion()
on an opened IndexReader.Reads version number from segments files. The version number is initialized with a timestamp and then increased by one for each change of the index.- Parameters:
directory
- where the index resides.- Returns:
- version number.
- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
-
getCommitUserData
@Deprecated public static Map<String,String> getCommitUserData(Directory directory) throws CorruptIndexException, IOException
Deprecated.CallgetIndexCommit()
on an open IndexReader, and then callIndexCommit.getUserData()
.Reads commitUserData, previously passed toIndexWriter.commit(Map)
, from current index segments file. This will return null ifIndexWriter.commit(Map)
has never been called for this index.- Parameters:
directory
- where the index resides.- Returns:
- commit userData.
- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
-
getVersion
public long getVersion()
Version number when this IndexReader was opened. Not implemented in the IndexReader base class.If this reader is based on a Directory (ie, was created by calling
open(org.apache.lucene.store.Directory)
, oropenIfChanged(org.apache.lucene.index.IndexReader)
on a reader based on a Directory), then this method returns the version recorded in the commit that the reader opened. This version is advanced every timeIndexWriter.commit()
is called.- Throws:
UnsupportedOperationException
- unless overridden in subclass
-
getCommitUserData
@Deprecated public Map<String,String> getCommitUserData()
Deprecated.CallgetIndexCommit()
and then callIndexCommit.getUserData()
.Retrieve the String userData optionally passed to IndexWriter#commit. This will return null ifIndexWriter.commit(Map)
has never been called for this index.
-
isCurrent
public boolean isCurrent() throws CorruptIndexException, IOException
Check whether any new changes have occurred to the index since this reader was opened.If this reader is based on a Directory (ie, was created by calling
open(org.apache.lucene.store.Directory)
, oropenIfChanged(org.apache.lucene.index.IndexReader)
on a reader based on a Directory), then this method checks if any further commits (seeIndexWriter.commit()
have occurred in that directory).If instead this reader is a near real-time reader (ie, obtained by a call to
IndexWriter.getReader()
, or by callingopenIfChanged(org.apache.lucene.index.IndexReader)
on a near real-time reader), then this method checks if either a new commmit has occurred, or any new uncommitted changes have taken place via the writer. Note that even if the writer has only performed merging, this method will still return false.In any event, if this returns false, you should call
openIfChanged(org.apache.lucene.index.IndexReader)
to get a new reader that sees the changes.- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO errorUnsupportedOperationException
- unless overridden in subclass
-
isOptimized
@Deprecated public boolean isOptimized()
Deprecated.Check segment count usinggetSequentialSubReaders()
instead.
-
getTermFreqVectors
public abstract TermFreqVector[] getTermFreqVectors(int docNumber) throws IOException
Return an array of term frequency vectors for the specified document. The array contains a vector for each vectorized field in the document. Each vector contains terms and frequencies for all terms in a given vectorized field. If no such fields existed, the method returns null. The term vectors that are returned may either be of typeTermFreqVector
or of typeTermPositionVector
if positions or offsets have been stored.- Parameters:
docNumber
- document for which term frequency vectors are returned- Returns:
- array of term frequency vectors. May be null if no term vectors have been stored for the specified document.
- Throws:
IOException
- if index cannot be accessed- See Also:
Field.TermVector
-
getTermFreqVector
public abstract TermFreqVector getTermFreqVector(int docNumber, String field) throws IOException
Return a term frequency vector for the specified document and field. The returned vector contains terms and frequencies for the terms in the specified field of this document, if the field had the storeTermVector flag set. If termvectors had been stored with positions or offsets, aTermPositionVector
is returned.- Parameters:
docNumber
- document for which the term frequency vector is returnedfield
- field for which the term frequency vector is returned.- Returns:
- term frequency vector May be null if field does not exist in the specified document or term vector was not stored.
- Throws:
IOException
- if index cannot be accessed- See Also:
Field.TermVector
-
getTermFreqVector
public abstract void getTermFreqVector(int docNumber, String field, TermVectorMapper mapper) throws IOException
Load the Term Vector into a user-defined data structure instead of relying on the parallel arrays of theTermFreqVector
.- Parameters:
docNumber
- The number of the document to load the vector forfield
- The name of the field to loadmapper
- TheTermVectorMapper
to process the vector. Must not be null- Throws:
IOException
- if term vectors cannot be accessed or if they do not exist on the field and doc. specified.
-
getTermFreqVector
public abstract void getTermFreqVector(int docNumber, TermVectorMapper mapper) throws IOException
Map all the term vectors for all fields in a Document- Parameters:
docNumber
- The number of the document to load the vector formapper
- TheTermVectorMapper
to process the vector. Must not be null- Throws:
IOException
- if term vectors cannot be accessed or if they do not exist on the field and doc. specified.
-
indexExists
public static boolean indexExists(Directory directory) throws IOException
Returnstrue
if an index exists at the specified directory.- Parameters:
directory
- the directory to check for an index- Returns:
true
if an index exists;false
otherwise- Throws:
IOException
- if there is a problem with accessing the index
-
numDocs
public abstract int numDocs()
Returns the number of documents in this index.
-
maxDoc
public abstract int maxDoc()
Returns one greater than the largest possible document number. This may be used to, e.g., determine how big to allocate an array which will have an element for every document number in an index.
-
numDeletedDocs
public final int numDeletedDocs()
Returns the number of deleted documents.
-
document
public final Document document(int n) throws CorruptIndexException, IOException
Returns the stored fields of then
thDocument
in this index.NOTE: for performance reasons, this method does not check if the requested document is deleted, and therefore asking for a deleted document may yield unspecified results. Usually this is not required, however you can call
isDeleted(int)
with the requested document ID to verify the document is not deleted.- Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
-
document
public abstract Document document(int n, FieldSelector fieldSelector) throws CorruptIndexException, IOException
Get theDocument
at then
th position. TheFieldSelector
may be used to determine whatField
s to load and how they should be loaded. NOTE: If this Reader (more specifically, the underlyingFieldsReader
) is closed before the lazyField
is loaded an exception may be thrown. If you want the value of a lazyField
to be available after closing you must explicitly load it or fetch the Document again with a new loader.NOTE: for performance reasons, this method does not check if the requested document is deleted, and therefore asking for a deleted document may yield unspecified results. Usually this is not required, however you can call
isDeleted(int)
with the requested document ID to verify the document is not deleted.- Parameters:
n
- Get the document at then
th positionfieldSelector
- TheFieldSelector
to use to determine what Fields should be loaded on the Document. May be null, in which case all Fields will be loaded.- Returns:
- The stored fields of the
Document
at the nth position - Throws:
CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error- See Also:
Fieldable
,FieldSelector
,SetBasedFieldSelector
,LoadFirstFieldSelector
-
isDeleted
public abstract boolean isDeleted(int n)
Returns true if document n has been deleted
-
hasDeletions
public abstract boolean hasDeletions()
Returns true if any documents have been deleted
-
hasNorms
public boolean hasNorms(String field) throws IOException
Returns true if there are norms stored for this field.- Throws:
IOException
-
norms
public abstract byte[] norms(String field) throws IOException
Returns the byte-encoded normalization factor for the named field of every document. This is used by the search code to score documents. Returns null if norms were not indexed for this field.- Throws:
IOException
- See Also:
AbstractField.setBoost(float)
-
norms
public abstract void norms(String field, byte[] bytes, int offset) throws IOException
Reads the byte-encoded normalization factor for the named field of every document. This is used by the search code to score documents.- Throws:
IOException
- See Also:
AbstractField.setBoost(float)
-
setNorm
@Deprecated public final void setNorm(int doc, String field, byte value) throws StaleReaderException, CorruptIndexException, LockObtainFailedException, IOException
Deprecated.Write support will be removed in Lucene 4.0. There will be no replacement for this method.Expert: Resets the normalization factor for the named field of the named document. The norm represents the product of the field'sboost
and itslength normalization
. Thus, to preserve the length normalization values when resetting this, one should base the new value upon the old. NOTE: If this field does not index norms, then this method throwsIllegalStateException
.- Throws:
StaleReaderException
- if the index has changed since this reader was openedCorruptIndexException
- if the index is corruptLockObtainFailedException
- if another writer has this index open (write.lock
could not be obtained)IOException
- if there is a low-level IO errorIllegalStateException
- if the field does not index norms- See Also:
norms(String)
,Similarity.decodeNormValue(byte)
-
doSetNorm
@Deprecated protected abstract void doSetNorm(int doc, String field, byte value) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. There will be no replacement for this method.Implements setNorm in subclass.- Throws:
CorruptIndexException
IOException
-
setNorm
@Deprecated public final void setNorm(int doc, String field, float value) throws StaleReaderException, CorruptIndexException, LockObtainFailedException, IOException
Deprecated.Write support will be removed in Lucene 4.0. There will be no replacement for this method.Expert: Resets the normalization factor for the named field of the named document.- Throws:
StaleReaderException
- if the index has changed since this reader was openedCorruptIndexException
- if the index is corruptLockObtainFailedException
- if another writer has this index open (write.lock
could not be obtained)IOException
- if there is a low-level IO error- See Also:
norms(String)
,Similarity.decodeNormValue(byte)
-
terms
public abstract TermEnum terms() throws IOException
Returns an enumeration of all the terms in the index. The enumeration is ordered by Term.compareTo(). Each term is greater than all that precede it in the enumeration. Note that after calling terms(),TermEnum.next()
must be called on the resulting enumeration before calling other methods such asTermEnum.term()
.- Throws:
IOException
- if there is a low-level IO error
-
terms
public abstract TermEnum terms(Term t) throws IOException
Returns an enumeration of all terms starting at a given term. If the given term does not exist, the enumeration is positioned at the first term greater than the supplied term. The enumeration is ordered by Term.compareTo(). Each term is greater than all that precede it in the enumeration.- Throws:
IOException
- if there is a low-level IO error
-
docFreq
public abstract int docFreq(Term t) throws IOException
Returns the number of documents containing the termt
.- Throws:
IOException
- if there is a low-level IO error
-
termDocs
public TermDocs termDocs(Term term) throws IOException
Returns an enumeration of all the documents which containterm
. For each document, the document number, the frequency of the term in that document is also provided, for use in search scoring. If term is null, then all non-deleted docs are returned with freq=1. Thus, this method implements the mapping:-
Term => <docNum, freq>*
The enumeration is ordered by document number. Each document number is greater than all that precede it in the enumeration.
- Throws:
IOException
- if there is a low-level IO error
-
termDocs
public abstract TermDocs termDocs() throws IOException
Returns an unpositionedTermDocs
enumerator.Note: the TermDocs returned is unpositioned. Before using it, ensure that you first position it with
TermDocs.seek(Term)
orTermDocs.seek(TermEnum)
.- Throws:
IOException
- if there is a low-level IO error
-
termPositions
public final TermPositions termPositions(Term term) throws IOException
Returns an enumeration of all the documents which containterm
. For each document, in addition to the document number and frequency of the term in that document, a list of all of the ordinal positions of the term in the document is available. Thus, this method implements the mapping:-
Term => <docNum, freq,
<pos1, pos2, ...
posfreq-1>
>*
This positional information facilitates phrase and proximity searching.
The enumeration is ordered by document number. Each document number is greater than all that precede it in the enumeration.
- Throws:
IOException
- if there is a low-level IO error
-
termPositions
public abstract TermPositions termPositions() throws IOException
Returns an unpositionedTermPositions
enumerator.- Throws:
IOException
- if there is a low-level IO error
-
deleteDocument
@Deprecated public final void deleteDocument(int docNum) throws StaleReaderException, CorruptIndexException, LockObtainFailedException, IOException
Deprecated.Write support will be removed in Lucene 4.0. UseIndexWriter.deleteDocuments(Term)
insteadDeletes the document numbereddocNum
. Once a document is deleted it will not appear in TermDocs or TermPostitions enumerations. Attempts to read its field with thedocument(int)
method will result in an error. The presence of this document may still be reflected in thedocFreq(org.apache.lucene.index.Term)
statistic, though this will be corrected eventually as the index is further modified.- Throws:
StaleReaderException
- if the index has changed since this reader was openedCorruptIndexException
- if the index is corruptLockObtainFailedException
- if another writer has this index open (write.lock
could not be obtained)IOException
- if there is a low-level IO error
-
doDelete
@Deprecated protected abstract void doDelete(int docNum) throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. UseIndexWriter.deleteDocuments(Term)
insteadImplements deletion of the document numbereddocNum
. Applications should calldeleteDocument(int)
ordeleteDocuments(Term)
.- Throws:
CorruptIndexException
IOException
-
deleteDocuments
@Deprecated public final int deleteDocuments(Term term) throws StaleReaderException, CorruptIndexException, LockObtainFailedException, IOException
Deprecated.Write support will be removed in Lucene 4.0. UseIndexWriter.deleteDocuments(Term)
insteadDeletes all documents that have a giventerm
indexed. This is useful if one uses a document field to hold a unique ID string for the document. Then to delete such a document, one merely constructs a term with the appropriate field and the unique ID string as its text and passes it to this method. SeedeleteDocument(int)
for information about when this deletion will become effective.- Returns:
- the number of documents deleted
- Throws:
StaleReaderException
- if the index has changed since this reader was openedCorruptIndexException
- if the index is corruptLockObtainFailedException
- if another writer has this index open (write.lock
could not be obtained)IOException
- if there is a low-level IO error
-
undeleteAll
@Deprecated public final void undeleteAll() throws StaleReaderException, CorruptIndexException, LockObtainFailedException, IOException
Deprecated.Write support will be removed in Lucene 4.0. There will be no replacement for this method.Undeletes all documents currently marked as deleted in this index.NOTE: this method can only recover documents marked for deletion but not yet removed from the index; when and how Lucene removes deleted documents is an implementation detail, subject to change from release to release. However, you can use
numDeletedDocs()
on the current IndexReader instance to see how many documents will be un-deleted.- Throws:
StaleReaderException
- if the index has changed since this reader was openedLockObtainFailedException
- if another writer has this index open (write.lock
could not be obtained)CorruptIndexException
- if the index is corruptIOException
- if there is a low-level IO error
-
doUndeleteAll
@Deprecated protected abstract void doUndeleteAll() throws CorruptIndexException, IOException
Deprecated.Write support will be removed in Lucene 4.0. There will be no replacement for this method.Implements actual undeleteAll() in subclass.- Throws:
CorruptIndexException
IOException
-
acquireWriteLock
@Deprecated protected void acquireWriteLock() throws IOException
Deprecated.Write support will be removed in Lucene 4.0.Does nothing by default. Subclasses that require a write lock for index modifications must implement this method.- Throws:
IOException
-
flush
@Deprecated public final void flush() throws IOException
Deprecated.Write support will be removed in Lucene 4.0.- Throws:
IOException
-
flush
@Deprecated public final void flush(Map<String,String> commitUserData) throws IOException
Deprecated.Write support will be removed in Lucene 4.0.- Parameters:
commitUserData
- Opaque Map (String -> String) that's recorded into the segments file in the index, and retrievable byIndexCommit.getUserData()
.- Throws:
IOException
-
commit
@Deprecated protected final void commit() throws IOException
Deprecated.Write support will be removed in Lucene 4.0.Commit changes resulting from delete, undeleteAll, or setNorm operations If an exception is hit, then either no changes or all changes will have been committed to the index (transactional semantics).- Throws:
IOException
- if there is a low-level IO error
-
commit
@Deprecated public final void commit(Map<String,String> commitUserData) throws IOException
Deprecated.Write support will be removed in Lucene 4.0.Commit changes resulting from delete, undeleteAll, or setNorm operations If an exception is hit, then either no changes or all changes will have been committed to the index (transactional semantics).- Throws:
IOException
- if there is a low-level IO error
-
doCommit
@Deprecated protected abstract void doCommit(Map<String,String> commitUserData) throws IOException
Deprecated.Write support will be removed in Lucene 4.0.Implements commit.- Throws:
IOException
-
close
public final void close() throws IOException
Closes files associated with this index. Also saves any new deletions to disk. No other methods should be called after this has been called.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Throws:
IOException
- if there is a low-level IO error
-
doClose
protected abstract void doClose() throws IOException
Implements close.- Throws:
IOException
-
getFieldInfos
public abstract FieldInfos getFieldInfos()
Get theFieldInfos
describing all fields in this reader. NOTE: do not make any changes to the returned FieldInfos!- WARNING: This API is experimental and might change in incompatible ways in the next release.
-
getIndexCommit
public IndexCommit getIndexCommit() throws IOException
Expert: return the IndexCommit that this reader has opened. This method is only implemented by those readers that correspond to a Directory with its own segments_N file.- Throws:
IOException
- WARNING: This API is experimental and might change in incompatible ways in the next release.
-
listCommits
public static Collection<IndexCommit> listCommits(Directory dir) throws IOException
Returns all commit points that exist in the Directory. Normally, because the default isKeepOnlyLastCommitDeletionPolicy
, there would be only one commit point. But if you're using a customIndexDeletionPolicy
then there could be many commits. Once you have a given commit, you can open a reader on it by callingopen(IndexCommit,boolean)
There must be at least one commit in the Directory, else this method throwsIndexNotFoundException
. Note that if a commit is in progress while this method is running, that commit may or may not be returned.- Returns:
- a sorted list of
IndexCommit
s, from oldest to latest. - Throws:
IOException
-
getSequentialSubReaders
public IndexReader[] getSequentialSubReaders()
Expert: returns the sequential sub readers that this reader is logically composed of. For example, IndexSearcher uses this API to drive searching by one sub reader at a time. If this reader is not composed of sequential child readers, it should return null. If this method returns an empty array, that means this reader is a null reader (for example a MultiReader that has no sub readers).NOTE: You should not try using sub-readers returned by this method to make any changes (setNorm, deleteDocument, etc.). While this might succeed for one composite reader (like MultiReader), it will most likely lead to index corruption for other readers (like DirectoryReader obtained through
open(org.apache.lucene.store.Directory)
. Use the parent reader directly.
-
getCoreCacheKey
public Object getCoreCacheKey()
Expert
-
getDeletesCacheKey
public Object getDeletesCacheKey()
Expert. Warning: this returns null if the reader has no deletions
-
getUniqueTermCount
public long getUniqueTermCount() throws IOException
Returns the number of unique terms (across all fields) in this reader. This method returns long, even though internally Lucene cannot handle more than 2^31 unique terms, for a possible future when this limitation is removed.- Throws:
UnsupportedOperationException
- if this count cannot be easily determined (eg Multi*Readers). Instead, you should callgetSequentialSubReaders()
and ask each sub reader for its unique term count.IOException
-
getTermInfosIndexDivisor
public int getTermInfosIndexDivisor()
For IndexReader implementations that use TermInfosReader to read terms, this returns the current indexDivisor as specified when the reader was opened.
-
-