org.apache.lucene.index

Class LeafReader

java.lang.Object

org.apache.lucene.index.IndexReader

org.apache.lucene.index.LeafReader

All Implemented Interfaces:

Closeable, AutoCloseable

Direct Known Subclasses:

CodecReader, FilterLeafReader, ParallelLeafReader

public abstract class LeafReader
extends IndexReader

LeafReader 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.CacheHelper, IndexReader.CacheKey, IndexReader.ClosedListener

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	LeafReader() Sole constructor.

Method Summary

Modifier and Type	Method and Description
abstract void	checkIntegrity() Checks consistency of this reader.
int	docFreq(Term term) Returns the number of documents containing the term.
abstract BinaryDocValues	getBinaryDocValues(String field) Returns BinaryDocValues for this field, or null if no binary doc values were indexed for this field.
LeafReaderContext	getContext() Expert: Returns the root IndexReaderContext for this IndexReader's sub-reader tree.
abstract IndexReader.CacheHelper	getCoreCacheHelper() Optional method: Return a IndexReader.CacheHelper that can be used to cache based on the content of this leaf regardless of deletions.
int	getDocCount(String field) Returns the number of documents that have at least one term 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 LeafMetaData	getMetaData() Return metadata about this leaf.
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 numeric doc values were indexed for this field.
abstract PointValues	getPointValues(String field) Returns the PointValues used for numeric or spatial searches for the given field, or null if there are no point fields.
abstract SortedDocValues	getSortedDocValues(String field) Returns SortedDocValues for this field, or null if no SortedDocValues were indexed for this field.
abstract SortedNumericDocValues	getSortedNumericDocValues(String field) Returns SortedNumericDocValues for this field, or null if no SortedNumericDocValues 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.
long	getSumTotalTermFreq(String field) Returns the sum of TermsEnum.totalTermFreq() for all terms in this field.
PostingsEnum	postings(Term term) Returns PostingsEnum for the specified term with PostingsEnum.FREQS.
PostingsEnum	postings(Term term, int flags) Returns PostingsEnum for the specified term.
abstract Terms	terms(String field) Returns the Terms index for this field, or null if it has none.
long	totalTermFreq(Term term) Returns the number of documents containing the term t.

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

close, decRef, doClose, document, document, document, ensureOpen, equals, getReaderCacheHelper, getRefCount, getTermVector, getTermVectors, hasDeletions, hashCode, incRef, leaves, maxDoc, numDeletedDocs, numDocs, registerParentReader, tryIncRef

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LeafReader

protected LeafReader()

Sole constructor. (For invocation by subclass constructors, typically implicit.)

Method Detail

getContext

public final LeafReaderContext 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 LeafReaderContext.

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

getCoreCacheHelper

public abstract IndexReader.CacheHelper getCoreCacheHelper()

Optional method: Return a IndexReader.CacheHelper that can be used to cache based on the content of this leaf regardless of deletions. Two readers that have the same data but different sets of deleted documents or doc values updates may be considered equal. Consider using IndexReader.getReaderCacheHelper() if you need deletions or dv updates to be taken into account.

A return value of null indicates that this reader is not suited for caching, which is typically the case for short-lived wrappers that alter the content of the wrapped leaf reader.

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

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. 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. 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. 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 abstract Terms terms(String field)
                     throws IOException

Returns the Terms index for this field, or null if it has none.

Throws:

IOException

postings

public final PostingsEnum postings(Term term,
                                   int flags)
                            throws IOException

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

NOTE: The returned PostingsEnum may contain deleted docs.

Throws:

IOException

See Also:

TermsEnum.postings(PostingsEnum)

postings

public final PostingsEnum postings(Term term)
                            throws IOException

Returns PostingsEnum for the specified term with PostingsEnum.FREQS.

Use this method if you only require documents and frequencies, and do not need any proximity data. This method is equivalent to postings(term, PostingsEnum.FREQS)

NOTE: The returned PostingsEnum may contain deleted docs.

Throws:

IOException

See Also:

postings(Term, int)

getNumericDocValues

public abstract NumericDocValues getNumericDocValues(String field)
                                              throws IOException

Returns NumericDocValues for this field, or null if no numeric doc values 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 binary doc values 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

getSortedNumericDocValues

public abstract SortedNumericDocValues getSortedNumericDocValues(String field)
                                                          throws IOException

Returns SortedNumericDocValues for this field, or null if no SortedNumericDocValues 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

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. Note: Implementations should cache the FieldInfos instance returned by this method such that subsequent calls to this method return the same instance.

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

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.

getPointValues

public abstract PointValues getPointValues(String field)
                                    throws IOException

Returns the PointValues used for numeric or spatial searches for the given field, or null if there are no point fields.

Throws:

IOException

checkIntegrity

public abstract void checkIntegrity()
                             throws IOException

Checks consistency of this reader.

Note that this may be costly in terms of I/O, e.g. may involve computing a checksum value against large data files.

Throws:

IOException

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

getMetaData

public abstract LeafMetaData getMetaData()

Return metadata about this leaf.

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