Class BaseCompositeReader<R extends IndexReader>
- 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<R>
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
- Direct Known Subclasses:
DirectoryReader
,MultiReader
,ParallelCompositeReader
public abstract class BaseCompositeReader<R extends IndexReader> extends CompositeReader
Base class for implementingCompositeReader
s based on an array of sub-readers. The implementing class has to add code for correctly refcounting and closing the sub-readers.User code will most likely use
MultiReader
to build a composite reader on a set of sub-readers (like severalDirectoryReader
s).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 theIndexReader
instance; use your own (non-Lucene) objects instead.- See Also:
MultiReader
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Nested Class Summary
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Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader
IndexReader.ReaderClosedListener
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Constructor Summary
Constructors Modifier Constructor Description protected
BaseCompositeReader(R[] subReaders)
Constructs aBaseCompositeReader
on the given subReaders.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
docFreq(Term term)
Returns the number of documents containing theterm
.void
document(int docID, StoredFieldVisitor visitor)
Expert: visits the fields of a stored document, for custom processing/loading of each field.int
getDocCount(java.lang.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.protected java.util.List<? extends R>
getSequentialSubReaders()
Expert: returns the sequential sub readers that this reader is logically composed of.long
getSumDocFreq(java.lang.String field)
Returns the sum ofTermsEnum.docFreq()
for all terms in this field, or -1 if this measure isn't stored by the codec.long
getSumTotalTermFreq(java.lang.String field)
Returns the sum ofTermsEnum.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).Fields
getTermVectors(int docID)
Retrieve term vectors for this document, or null if term vectors were not indexed.int
maxDoc()
Returns one greater than the largest possible document number.int
numDocs()
Returns the number of documents in this index.protected int
readerBase(int readerIndex)
Helper method for subclasses to get the docBase of the given sub-reader index.protected int
readerIndex(int docID)
Helper method for subclasses to get the corresponding reader for a doc IDlong
totalTermFreq(Term term)
Returns the total number of occurrences ofterm
across all documents (the sum of the freq() for each doc that has this term).-
Methods inherited from class org.apache.lucene.index.CompositeReader
getContext, toString
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Methods inherited from class org.apache.lucene.index.IndexReader
addReaderClosedListener, close, decRef, doClose, document, document, ensureOpen, equals, getCombinedCoreAndDeletesKey, getCoreCacheKey, getRefCount, getTermVector, hasDeletions, hashCode, incRef, leaves, numDeletedDocs, open, open, open, open, open, registerParentReader, removeReaderClosedListener, tryIncRef
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Constructor Detail
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BaseCompositeReader
protected BaseCompositeReader(R[] subReaders)
Constructs aBaseCompositeReader
on the given subReaders.- Parameters:
subReaders
- the wrapped sub-readers. This array is returned bygetSequentialSubReaders()
and used to resolve the correct subreader for docID-based methods. Please note: This array is not cloned and not protected for modification, the subclass is responsible to do this.
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Method Detail
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getTermVectors
public final Fields getTermVectors(int docID) throws java.io.IOException
Description copied from class:IndexReader
Retrieve term vectors for this document, or null if term vectors were not indexed. The returned Fields instance acts like a single-document inverted index (the docID will be 0).- Specified by:
getTermVectors
in classIndexReader
- Throws:
java.io.IOException
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numDocs
public final int numDocs()
Description copied from class:IndexReader
Returns the number of documents in this index.- Specified by:
numDocs
in classIndexReader
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maxDoc
public final 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 classIndexReader
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document
public final void document(int docID, StoredFieldVisitor visitor) throws java.io.IOException
Description copied from class:IndexReader
Expert: visits the fields of a stored document, for custom processing/loading of each field. If you simply want to load all fields, useIndexReader.document(int)
. If you want to load a subset, useDocumentStoredFieldVisitor
.- Specified by:
document
in classIndexReader
- Throws:
java.io.IOException
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docFreq
public final int docFreq(Term term) throws java.io.IOException
Description copied from class:IndexReader
Returns the number of documents containing theterm
. 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 classIndexReader
- Throws:
java.io.IOException
- See Also:
TermsEnum.docFreq()
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totalTermFreq
public final long totalTermFreq(Term term) throws java.io.IOException
Description copied from class:IndexReader
Returns the total number of occurrences ofterm
across all documents (the sum of the freq() for each doc that has this term). This will be -1 if the codec doesn't support this measure. Note that, like other term measures, this measure does not take deleted documents into account.- Specified by:
totalTermFreq
in classIndexReader
- Throws:
java.io.IOException
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getSumDocFreq
public final long getSumDocFreq(java.lang.String field) throws java.io.IOException
Description copied from class:IndexReader
Returns the sum ofTermsEnum.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 classIndexReader
- Throws:
java.io.IOException
- See Also:
Terms.getSumDocFreq()
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getDocCount
public final int getDocCount(java.lang.String field) throws java.io.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 classIndexReader
- Throws:
java.io.IOException
- See Also:
Terms.getDocCount()
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getSumTotalTermFreq
public final long getSumTotalTermFreq(java.lang.String field) throws java.io.IOException
Description copied from class:IndexReader
Returns the sum ofTermsEnum.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 classIndexReader
- Throws:
java.io.IOException
- See Also:
Terms.getSumTotalTermFreq()
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readerIndex
protected final int readerIndex(int docID)
Helper method for subclasses to get the corresponding reader for a doc ID
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readerBase
protected final int readerBase(int readerIndex)
Helper method for subclasses to get the docBase of the given sub-reader index.
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getSequentialSubReaders
protected final java.util.List<? extends R> getSequentialSubReaders()
Description copied from class:CompositeReader
Expert: returns the sequential sub readers that this reader is logically composed of. This method may not returnnull
.NOTE: In contrast to previous Lucene versions this method is no longer public, code that wants to get all
AtomicReader
s this composite is composed of should useIndexReader.leaves()
.- Specified by:
getSequentialSubReaders
in classCompositeReader
- See Also:
IndexReader.leaves()
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