Class MultiReader
- java.lang.Object
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- org.apache.lucene.index.IndexReader
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- org.apache.lucene.index.CompositeReader
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- org.apache.lucene.index.BaseCompositeReader<IndexReader>
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- org.apache.lucene.index.MultiReader
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- All Implemented Interfaces:
Closeable,AutoCloseable
public class MultiReader extends BaseCompositeReader<IndexReader>
ACompositeReaderwhich reads multiple indexes, appending their content. It can be used to create a view on several sub-readers (likeDirectoryReader) 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:
IndexReaderinstances 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 theIndexReaderinstance; use your own (non-Lucene) objects instead.
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader
IndexReader.CacheHelper, IndexReader.CacheKey, IndexReader.ClosedListener
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Field Summary
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Fields inherited from class org.apache.lucene.index.BaseCompositeReader
subReadersSorter
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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.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected voiddoClose()Implements close.IndexReader.CacheHelpergetReaderCacheHelper()Optional method: Return aIndexReader.CacheHelperthat 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, storedFields, termVectors, totalTermFreq
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Methods inherited from class org.apache.lucene.index.CompositeReader
getContext, toString
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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
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Constructor Detail
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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
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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
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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 notnullis used for sorting sub readers.closeSubReaders- indicates whether the subreaders should be closed when this MultiReader is closed- Throws:
IOException
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Method Detail
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getReaderCacheHelper
public IndexReader.CacheHelper getReaderCacheHelper()
Description copied from class:IndexReaderOptional method: Return aIndexReader.CacheHelperthat 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
nullindicates 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:
getReaderCacheHelperin classIndexReader
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doClose
protected void doClose() throws IOExceptionDescription copied from class:IndexReaderImplements close.- Specified by:
doClosein classIndexReader- Throws:
IOException
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