org.apache.lucene.index

Class SegmentReader

java.lang.Object

org.apache.lucene.index.IndexReader

org.apache.lucene.index.SegmentReader

All Implemented Interfaces:

Closeable, Cloneable

public class SegmentReader
extends IndexReader
implements Cloneable

IndexReader implementation over a single segment.

Instances pointing to the same segment (but with different deletes, etc) may share the same core data.

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

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SegmentReader.CoreClosedListener Called when the shared core for this SegmentReader is closed.

Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader

IndexReader.ReaderClosedListener

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	readOnly Deprecated.

Fields inherited from class org.apache.lucene.index.IndexReader

hasChanges

Constructor Summary

Constructors

Constructor and Description
SegmentReader()

Method Summary

Methods

Modifier and Type	Method and Description
void	addCoreClosedListener(SegmentReader.CoreClosedListener listener) Expert: adds a CoreClosedListener to this reader's shared core
Object	clone() Efficiently clones the IndexReader (sharing most internal state).
IndexReader	clone(boolean openReadOnly) Deprecated.
protected BitVector	cloneDeletedDocs(BitVector bv) Deprecated.
protected byte[]	cloneNormBytes(byte[] bytes) Deprecated.
Directory	directory() Returns the directory this index resides in.
int	docFreq(Term t) Returns the number of documents containing the term t.
protected void	doClose() Implements close.
protected void	doCommit(Map<String,String> commitUserData) Deprecated.
Document	document(int n, FieldSelector fieldSelector) Get the Document at the n th position.
protected void	doDelete(int docNum) Deprecated.
protected IndexReader	doOpenIfChanged() If the index has changed since it was opened, open and return a new reader; else, return null.
protected IndexReader	doOpenIfChanged(boolean openReadOnly) Deprecated.
protected void	doSetNorm(int doc, String field, byte value) Deprecated.
protected void	doUndeleteAll() Deprecated.
static SegmentReader	get(boolean readOnly, Directory dir, SegmentInfo si, int readBufferSize, boolean doOpenStores, int termInfosIndexDivisor)
static SegmentReader	get(boolean readOnly, SegmentInfo si, int termInfosIndexDivisor)
Object	getCoreCacheKey() Expert
Object	getDeletesCacheKey() Expert.
FieldInfos	getFieldInfos() Get the FieldInfos describing all fields in this reader.
String	getSegmentName() Return the name of the segment this reader is reading.
TermFreqVector	getTermFreqVector(int docNumber, String field) Return a term frequency vector for the specified document and field.
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 the TermFreqVector.
void	getTermFreqVector(int docNumber, TermVectorMapper mapper) Map all the term vectors for all fields in a Document
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.
boolean	hasDeletions() Returns true if any documents have been deleted
boolean	hasNorms(String field) Returns true if there are norms stored for this field.
boolean	isDeleted(int n) Returns true if document n has been deleted
int	maxDoc() Returns one greater than the largest possible document number.
byte[]	norms(String field) Returns the byte-encoded normalization factor for the named field of every document.
void	norms(String field, byte[] bytes, int offset) Read norms into a pre-allocated array.
int	numDocs() Returns the number of documents in this index.
TermDocs	rawTermDocs(Term term) Expert: returns an enumeration of the documents that contain term, including deleted documents (which are normally filtered out).
void	removeCoreClosedListener(SegmentReader.CoreClosedListener listener) Expert: removes a CoreClosedListener from this reader's shared core
TermDocs	termDocs() Returns an unpositioned TermDocs enumerator.
TermDocs	termDocs(Term term) Returns an enumeration of all the documents which contain term.
TermPositions	termPositions() Returns an unpositioned TermPositions enumerator.
TermEnum	terms() Returns an enumeration of all the terms in the index.
TermEnum	terms(Term t) Returns an enumeration of all terms starting at a given term.
String	toString()

Methods inherited from class org.apache.lucene.index.IndexReader

acquireWriteLock, addReaderClosedListener, close, commit, commit, decRef, deleteDocument, deleteDocuments, document, doOpenIfChanged, doOpenIfChanged, ensureOpen, flush, flush, getCommitUserData, getCommitUserData, getCurrentVersion, getIndexCommit, getRefCount, getSequentialSubReaders, getVersion, incRef, indexExists, isCurrent, isOptimized, lastModified, listCommits, numDeletedDocs, open, open, open, open, open, open, open, open, open, open, open, openIfChanged, openIfChanged, openIfChanged, openIfChanged, removeReaderClosedListener, reopen, reopen, reopen, reopen, setNorm, setNorm, termPositions, tryIncRef, undeleteAll

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

readOnly

@Deprecated
protected boolean readOnly

Deprecated.

Constructor Detail

SegmentReader

public SegmentReader()

Method Detail

get

public static SegmentReader get(boolean readOnly,
                SegmentInfo si,
                int termInfosIndexDivisor)
                         throws CorruptIndexException,
                                IOException

Throws:

CorruptIndexException - if the index is corrupt

IOException - if there is a low-level IO error

get

public static SegmentReader get(boolean readOnly,
                Directory dir,
                SegmentInfo si,
                int readBufferSize,
                boolean doOpenStores,
                int termInfosIndexDivisor)
                         throws CorruptIndexException,
                                IOException

Throws:

CorruptIndexException - if the index is corrupt

IOException - if there is a low-level IO error

cloneNormBytes

@Deprecated
protected byte[] cloneNormBytes(byte[] bytes)

Deprecated.

Clones the norm bytes. May be overridden by subclasses. New and experimental.

Parameters:

bytes - Byte array to clone

Returns:

New BitVector

cloneDeletedDocs

@Deprecated
protected BitVector cloneDeletedDocs(BitVector bv)

Deprecated.

Clones the deleteDocs BitVector. May be overridden by subclasses. New and experimental.

Parameters:

bv - BitVector to clone

Returns:

New BitVector

clone

public final Object clone()

Description copied from class: IndexReader

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 IndexReader.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.

Overrides:

clone in class IndexReader

clone

@Deprecated
public final IndexReader clone(boolean openReadOnly)
                        throws CorruptIndexException,
                               IOException

Deprecated.

Clones the IndexReader and optionally changes readOnly. A readOnly reader cannot open a writeable reader.

Overrides:

clone in class IndexReader

Throws:

CorruptIndexException - if the index is corrupt

IOException - if there is a low-level IO error

doOpenIfChanged

protected IndexReader doOpenIfChanged()
                               throws CorruptIndexException,
                                      IOException

Description copied from class: IndexReader

If the index has changed since it was opened, open and return a new reader; else, return null.

Overrides:

doOpenIfChanged in class IndexReader

Throws:

CorruptIndexException

IOException

See Also:

IndexReader.openIfChanged(IndexReader)

doOpenIfChanged

@Deprecated
protected IndexReader doOpenIfChanged(boolean openReadOnly)
                               throws CorruptIndexException,
                                      IOException

Deprecated.

If the index has changed since it was opened, open and return a new reader; else, return null.

Overrides:

doOpenIfChanged in class IndexReader

Throws:

CorruptIndexException

IOException

See Also:

IndexReader.openIfChanged(IndexReader, boolean)

doCommit

@Deprecated
protected void doCommit(Map<String,String> commitUserData)
                 throws IOException

Deprecated.

Implements commit.

Specified by:

doCommit in class IndexReader

Throws:

IOException

doClose

protected void doClose()
                throws IOException

Description copied from class: IndexReader

Implements close.

Specified by:

doClose in class IndexReader

Throws:

IOException

hasDeletions

public boolean hasDeletions()

Description copied from class: IndexReader

Returns true if any documents have been deleted

Specified by:

hasDeletions in class IndexReader

doDelete

@Deprecated
protected void doDelete(int docNum)

Deprecated.

Implements deletion of the document numbered docNum. Applications should call IndexReader.deleteDocument(int) or IndexReader.deleteDocuments(Term).

Specified by:

doDelete in class IndexReader

doUndeleteAll

@Deprecated
protected void doUndeleteAll()

Deprecated.

Implements actual undeleteAll() in subclass.

Specified by:

doUndeleteAll in class IndexReader

terms

public TermEnum terms()

Description copied from class: IndexReader

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 as TermEnum.term().

Specified by:

terms in class IndexReader

terms

public TermEnum terms(Term t)
               throws IOException

Description copied from class: IndexReader

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.

Specified by:

terms in class IndexReader

Throws:

IOException - if there is a low-level IO error

getFieldInfos

public FieldInfos getFieldInfos()

Description copied from class: IndexReader

Get the FieldInfos describing all fields in this reader. NOTE: do not make any changes to the returned FieldInfos!

Specified by:

getFieldInfos in class IndexReader

document

public Document document(int n,
                FieldSelector fieldSelector)
                  throws CorruptIndexException,
                         IOException

Description copied from class: IndexReader

Get the Document at the n ^th position. The FieldSelector may be used to determine what Fields to load and how they should be loaded. NOTE: If this Reader (more specifically, the underlying FieldsReader) is closed before the lazy Field is loaded an exception may be thrown. If you want the value of a lazy Field 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 IndexReader.isDeleted(int) with the requested document ID to verify the document is not deleted.

Specified by:

document in class IndexReader

Parameters:

n - Get the document at the n^th position

fieldSelector - The FieldSelector 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 corrupt

IOException - if there is a low-level IO error

See Also:

Fieldable, FieldSelector, SetBasedFieldSelector, LoadFirstFieldSelector

isDeleted

public boolean isDeleted(int n)

Description copied from class: IndexReader

Returns true if document n has been deleted

Specified by:

isDeleted in class IndexReader

termDocs

public TermDocs termDocs(Term term)
                  throws IOException

Description copied from class: IndexReader

Returns an enumeration of all the documents which contain term. 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.

Overrides:

termDocs in class IndexReader

Throws:

IOException - if there is a low-level IO error

rawTermDocs

public TermDocs rawTermDocs(Term term)
                     throws IOException

Expert: returns an enumeration of the documents that contain term, including deleted documents (which are normally filtered out).

Throws:

IOException

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

termDocs

public TermDocs termDocs()
                  throws IOException

Description copied from class: IndexReader

Returns an unpositioned TermDocs enumerator.

Note: the TermDocs returned is unpositioned. Before using it, ensure that you first position it with TermDocs.seek(Term) or TermDocs.seek(TermEnum).

Specified by:

termDocs in class IndexReader

Throws:

IOException - if there is a low-level IO error

termPositions

public TermPositions termPositions()
                            throws IOException

Description copied from class: IndexReader

Returns an unpositioned TermPositions enumerator.

Specified by:

termPositions in class IndexReader

Throws:

IOException - if there is a low-level IO error

docFreq

public int docFreq(Term t)
            throws IOException

Description copied from class: IndexReader

Returns the number of documents containing the term t.

Specified by:

docFreq in class IndexReader

Throws:

IOException - if there is a low-level IO error

numDocs

public int numDocs()

Description copied from class: IndexReader

Returns the number of documents in this index.

Specified by:

numDocs in class IndexReader

maxDoc

public int maxDoc()

Description copied from class: IndexReader

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.

Specified by:

maxDoc in class IndexReader

hasNorms

public boolean hasNorms(String field)

Description copied from class: IndexReader

Returns true if there are norms stored for this field.

Overrides:

hasNorms in class IndexReader

norms

public byte[] norms(String field)
             throws IOException

Description copied from class: IndexReader

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.

Specified by:

norms in class IndexReader

Throws:

IOException

See Also:

AbstractField.setBoost(float)

doSetNorm

@Deprecated
protected void doSetNorm(int doc,
                        String field,
                        byte value)
                  throws IOException

Deprecated.

Implements setNorm in subclass.

Specified by:

doSetNorm in class IndexReader

Throws:

IOException

norms

public void norms(String field,
         byte[] bytes,
         int offset)
           throws IOException

Read norms into a pre-allocated array.

Specified by:

norms in class IndexReader

Throws:

IOException

See Also:

AbstractField.setBoost(float)

getTermFreqVector

public TermFreqVector getTermFreqVector(int docNumber,
                               String field)
                                 throws IOException

Return a term frequency vector for the specified document and field. The vector returned contains term numbers and frequencies for all terms in the specified field of this document, if the field had storeTermVector flag set. If the flag was not set, the method returns null.

Specified by:

getTermFreqVector in class IndexReader

Parameters:

docNumber - document for which the term frequency vector is returned

field - 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

See Also:

Field.TermVector

getTermFreqVector

public void getTermFreqVector(int docNumber,
                     String field,
                     TermVectorMapper mapper)
                       throws IOException

Description copied from class: IndexReader

Load the Term Vector into a user-defined data structure instead of relying on the parallel arrays of the TermFreqVector.

Specified by:

getTermFreqVector in class IndexReader

Parameters:

docNumber - The number of the document to load the vector for

field - The name of the field to load

mapper - The TermVectorMapper 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 void getTermFreqVector(int docNumber,
                     TermVectorMapper mapper)
                       throws IOException

Description copied from class: IndexReader

Map all the term vectors for all fields in a Document

Specified by:

getTermFreqVector in class IndexReader

Parameters:

docNumber - The number of the document to load the vector for

mapper - The TermVectorMapper 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.

getTermFreqVectors

public 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 vector contains term numbers and frequencies for all terms in a given vectorized field. If no such fields existed, the method returns null.

Specified by:

getTermFreqVectors in class IndexReader

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

See Also:

Field.TermVector

toString

public String toString()

Overrides:

toString in class IndexReader

getSegmentName

public String getSegmentName()

Return the name of the segment this reader is reading.

directory

public Directory directory()

Returns the directory this index resides in.

Overrides:

directory in class IndexReader

getCoreCacheKey

public final Object getCoreCacheKey()

Description copied from class: IndexReader

Expert

Overrides:

getCoreCacheKey in class IndexReader

getDeletesCacheKey

public Object getDeletesCacheKey()

Description copied from class: IndexReader

Expert. Warning: this returns null if the reader has no deletions

Overrides:

getDeletesCacheKey in class IndexReader

getUniqueTermCount

public long getUniqueTermCount()

Description copied from class: IndexReader

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.

Overrides:

getUniqueTermCount in class IndexReader

getTermInfosIndexDivisor

public int getTermInfosIndexDivisor()

Description copied from class: IndexReader

For IndexReader implementations that use TermInfosReader to read terms, this returns the current indexDivisor as specified when the reader was opened.

Overrides:

getTermInfosIndexDivisor in class IndexReader

addCoreClosedListener

public void addCoreClosedListener(SegmentReader.CoreClosedListener listener)

Expert: adds a CoreClosedListener to this reader's shared core

removeCoreClosedListener

public void removeCoreClosedListener(SegmentReader.CoreClosedListener listener)

Expert: removes a CoreClosedListener from this reader's shared core