Package org.apache.lucene.index

Class MultiReader

java.lang.Object

org.apache.lucene.index.IndexReader

org.apache.lucene.index.CompositeReader

org.apache.lucene.index.BaseCompositeReader<IndexReader>

org.apache.lucene.index.MultiReader

All Implemented Interfaces:

Closeable, AutoCloseable

public class MultiReader
extends BaseCompositeReader<IndexReader>

A CompositeReader which reads multiple indexes, appending their content. It can be used to create a view on several sub-readers (like DirectoryReader) and execute searches on it.

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

Field Summary

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

subReadersSorter

Constructor Summary

Constructors

Constructor	Description
MultiReader(IndexReader... subReaders)	Construct a MultiReader aggregating the named set of (sub)readers.
MultiReader(IndexReader[] subReaders, boolean closeSubReaders)	Construct a MultiReader aggregating the named set of (sub)readers.
MultiReader(IndexReader[] subReaders, Comparator<IndexReader> subReadersSorter, boolean closeSubReaders)	Construct a MultiReader aggregating the named set of (sub)readers.

Method Summary

Modifier and Type	Method	Description
protected void	doClose()	Implements close.
IndexReader.CacheHelper	getReaderCacheHelper()	Optional method: Return a IndexReader.CacheHelper that can be used to cache based on the content of this reader.

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

docFreq, document, getDocCount, getSequentialSubReaders, getSumDocFreq, getSumTotalTermFreq, getTermVectors, maxDoc, numDocs, readerBase, readerIndex, totalTermFreq

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

getContext, toString

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

close, decRef, document, document, ensureOpen, equals, getRefCount, getTermVector, hasDeletions, hashCode, incRef, leaves, notifyReaderClosedListeners, numDeletedDocs, registerParentReader, tryIncRef

Methods inherited from class java.lang.Object

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

Constructor Details

MultiReader

public MultiReader(IndexReader... subReaders)
            throws IOException

Construct a MultiReader aggregating the named set of (sub)readers.

Note that all subreaders are closed if this Multireader is closed.

Parameters:

subReaders - set of (sub)readers

Throws:

IOException

MultiReader

public MultiReader(IndexReader[] subReaders,
 boolean closeSubReaders)
            throws IOException

Construct a MultiReader aggregating the named set of (sub)readers.

Parameters:

subReaders - set of (sub)readers; this array will be cloned.

closeSubReaders - indicates whether the subreaders should be closed when this MultiReader is closed

Throws:

IOException

MultiReader

public MultiReader(IndexReader[] subReaders,
 Comparator<IndexReader> subReadersSorter,
 boolean closeSubReaders)
            throws IOException

Construct a MultiReader aggregating the named set of (sub)readers.

Parameters:

subReaders - set of (sub)readers; this array will be cloned.

subReadersSorter - – a comparator, that if not null is used for sorting sub readers.

closeSubReaders - indicates whether the subreaders should be closed when this MultiReader is closed

Throws:

IOException

Method Details

getReaderCacheHelper

public IndexReader.CacheHelper getReaderCacheHelper()

Description copied from class: IndexReader

Optional method: Return a IndexReader.CacheHelper that can be used to cache based on the content of this reader. Two readers that have different data or different sets of deleted documents will be considered different.

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 reader.

Specified by:

getReaderCacheHelper in class IndexReader

doClose

protected void doClose()
                throws IOException

Description copied from class: IndexReader

Implements close.

Specified by:

doClose in class IndexReader

Throws:

IOException