Package org.apache.lucene.index

Class AtomicReader

java.lang.Object

org.apache.lucene.index.IndexReader

org.apache.lucene.index.AtomicReader

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

FilterAtomicReader, ParallelAtomicReader, SegmentReader, SlowCompositeReaderWrapper

public abstract class AtomicReader
extends IndexReader

AtomicReader 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. IndexReaders implemented by this subclass do not consist of several sub-readers, they are atomic. They support retrieval of stored fields, doc values, terms, and postings.

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.

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 the IndexReader instance; use your own (non-Lucene) objects instead.

Nested Class Summary

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

IndexReader.ReaderClosedListener

Method Summary

Modifier and Type	Method	Description
int	docFreq(Term term)	Returns the number of documents containing the term.
abstract Fields	fields()	Returns Fields for this reader.
abstract BinaryDocValues	getBinaryDocValues(String field)	Returns BinaryDocValues for this field, or null if no BinaryDocValues were indexed for this field.
AtomicReaderContext	getContext()	Expert: Returns the root IndexReaderContext for this IndexReader's sub-reader tree.
int	getDocCount(String field)	Returns the number of documents that have at least one term for this field, or -1 if this measure isn't stored by the codec.
abstract Bits	getDocsWithField(String field)	Returns a Bits at the size of reader.maxDoc(), with turned on bits for each docid that does have a value for this field, or null if no DocValues were indexed for this field.
abstract FieldInfos	getFieldInfos()	Get the FieldInfos describing all fields in this reader.
abstract Bits	getLiveDocs()	Returns the Bits representing live (not deleted) docs.
abstract NumericDocValues	getNormValues(String field)	Returns NumericDocValues representing norms for this field, or null if no NumericDocValues were indexed.
abstract NumericDocValues	getNumericDocValues(String field)	Returns NumericDocValues for this field, or null if no NumericDocValues were indexed for this field.
abstract SortedDocValues	getSortedDocValues(String field)	Returns SortedDocValues for this field, or null if no SortedDocValues were indexed for this field.
abstract SortedSetDocValues	getSortedSetDocValues(String field)	Returns SortedSetDocValues for this field, or null if no SortedSetDocValues were indexed for this field.
long	getSumDocFreq(String field)	Returns the sum of TermsEnum.docFreq() for all terms in this field, or -1 if this measure isn't stored by the codec.
long	getSumTotalTermFreq(String field)	Returns the sum of TermsEnum.totalTermFreq() for all terms in this field, or -1 if this measure isn't stored by the codec (or if this fields omits term freq and positions).
boolean	hasNorms(String field)	Deprecated. (4.0) use getFieldInfos() and check FieldInfo.hasNorms() for the field instead.
DocsEnum	termDocsEnum(Term term)	Returns DocsEnum for the specified term.
DocsAndPositionsEnum	termPositionsEnum(Term term)	Returns DocsAndPositionsEnum for the specified term.
Terms	terms(String field)	This may return null if the field does not exist.
long	totalTermFreq(Term term)	Returns the number of documents containing the term t.

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

addReaderClosedListener, close, decRef, document, document, document, equals, getCombinedCoreAndDeletesKey, getCoreCacheKey, getRefCount, getTermVector, getTermVectors, hasDeletions, hashCode, incRef, leaves, maxDoc, numDeletedDocs, numDocs, open, open, open, open, open, registerParentReader, removeReaderClosedListener, tryIncRef

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Method Detail

getContext

public final AtomicReaderContext getContext()

Description copied from class: IndexReader

Expert: Returns the root IndexReaderContext for this IndexReader's sub-reader tree.

Iff this reader is composed of sub readers, i.e. this reader being a composite reader, this method returns a CompositeReaderContext holding the reader's direct children as well as a view of the reader tree's atomic leaf contexts. All sub- IndexReaderContext instances referenced from this readers top-level context are private to this reader and are not shared with another context tree. For example, IndexSearcher uses this API to drive searching by one atomic leaf reader at a time. If this reader is not composed of child readers, this method returns an AtomicReaderContext.

Note: Any of the sub-CompositeReaderContext instances referenced from this top-level context do not support CompositeReaderContext.leaves(). Only the top-level context maintains the convenience leaf-view for performance reasons.

Specified by:

getContext in class IndexReader

hasNorms

@Deprecated
public final boolean hasNorms(String field)
                       throws IOException

Deprecated.

(4.0) use getFieldInfos() and check FieldInfo.hasNorms() for the field instead.

Returns true if there are norms stored for this field.

Throws:

IOException

fields

public abstract Fields fields()
                       throws IOException

Returns Fields for this reader. This method may return null if the reader has no postings.

Throws:

IOException

docFreq

public final int docFreq(Term term)
                  throws IOException

Description copied from class: IndexReader

Returns the number of documents containing the term. This method returns 0 if the term or field does not exists. This method does not take into account deleted documents that have not yet been merged away.

Specified by:

docFreq in class IndexReader

Throws:

IOException

See Also:

TermsEnum.docFreq()

totalTermFreq

public final long totalTermFreq(Term term)
                         throws IOException

Returns the number of documents containing the term t. This method returns 0 if the term or field does not exists. This method does not take into account deleted documents that have not yet been merged away.

Specified by:

totalTermFreq in class IndexReader

Throws:

IOException

getSumDocFreq

public final long getSumDocFreq(String field)
                         throws IOException

Description copied from class: IndexReader

Returns the sum of TermsEnum.docFreq() for all terms in this field, or -1 if this measure isn't stored by the codec. Note that, just like other term measures, this measure does not take deleted documents into account.

Specified by:

getSumDocFreq in class IndexReader

Throws:

IOException

See Also:

Terms.getSumDocFreq()

getDocCount

public final int getDocCount(String field)
                      throws IOException

Description copied from class: IndexReader

Returns the number of documents that have at least one term for this field, or -1 if this measure isn't stored by the codec. Note that, just like other term measures, this measure does not take deleted documents into account.

Specified by:

getDocCount in class IndexReader

Throws:

IOException

See Also:

Terms.getDocCount()

getSumTotalTermFreq

public final long getSumTotalTermFreq(String field)
                               throws IOException

Description copied from class: IndexReader

Returns the sum of TermsEnum.totalTermFreq() for all terms in this field, or -1 if this measure isn't stored by the codec (or if this fields omits term freq and positions). Note that, just like other term measures, this measure does not take deleted documents into account.

Specified by:

getSumTotalTermFreq in class IndexReader

Throws:

IOException

See Also:

Terms.getSumTotalTermFreq()

terms

public final Terms terms(String field)
                  throws IOException

This may return null if the field does not exist.

Throws:

IOException

termDocsEnum

public final DocsEnum termDocsEnum(Term term)
                            throws IOException

Returns DocsEnum for the specified term. This will return null if either the field or term does not exist.

Throws:

IOException

See Also:

TermsEnum.docs(Bits, DocsEnum)

termPositionsEnum

public final DocsAndPositionsEnum termPositionsEnum(Term term)
                                             throws IOException

Returns DocsAndPositionsEnum for the specified term. This will return null if the field or term does not exist or positions weren't indexed.

Throws:

IOException

See Also:

TermsEnum.docsAndPositions(Bits, DocsAndPositionsEnum)

getNumericDocValues

public abstract NumericDocValues getNumericDocValues(String field)
                                              throws IOException

Returns NumericDocValues for this field, or null if no NumericDocValues were indexed for this field. The returned instance should only be used by a single thread.

Throws:

IOException

getBinaryDocValues

public abstract BinaryDocValues getBinaryDocValues(String field)
                                            throws IOException

Returns BinaryDocValues for this field, or null if no BinaryDocValues were indexed for this field. The returned instance should only be used by a single thread.

Throws:

IOException

getSortedDocValues

public abstract SortedDocValues getSortedDocValues(String field)
                                            throws IOException

Returns SortedDocValues for this field, or null if no SortedDocValues were indexed for this field. The returned instance should only be used by a single thread.

Throws:

IOException

getSortedSetDocValues

public abstract SortedSetDocValues getSortedSetDocValues(String field)
                                                  throws IOException

Returns SortedSetDocValues for this field, or null if no SortedSetDocValues were indexed for this field. The returned instance should only be used by a single thread.

Throws:

IOException

getDocsWithField

public abstract Bits getDocsWithField(String field)
                               throws IOException

Returns a Bits at the size of reader.maxDoc(), with turned on bits for each docid that does have a value for this field, or null if no DocValues were indexed for this field. The returned instance should only be used by a single thread

Throws:

IOException

getNormValues

public abstract NumericDocValues getNormValues(String field)
                                        throws IOException

Returns NumericDocValues representing norms for this field, or null if no NumericDocValues were indexed. The returned instance should only be used by a single thread.

Throws:

IOException

getFieldInfos

public abstract FieldInfos getFieldInfos()

Get the FieldInfos describing all fields in this reader.

getLiveDocs

public abstract Bits getLiveDocs()

Returns the Bits representing live (not deleted) docs. A set bit indicates the doc ID has not been deleted. If this method returns null it means there are no deleted documents (all documents are live). The returned instance has been safely published for use by multiple threads without additional synchronization.