Class CompositeReader
- All Implemented Interfaces:
Closeable
,AutoCloseable
- Direct Known Subclasses:
BaseCompositeReader
AtomicReaderContext
for all sub-readers via IndexReader.leaves()
.
Alternatively, you can mimic an AtomicReader
(with a serious slowdown),
by wrapping composite readers with SlowCompositeReaderWrapper
.
IndexReader instances for indexes on disk are usually constructed
with a call to one of the static DirectoryReader.open()
methods,
e.g. DirectoryReader.open(Directory)
. DirectoryReader
implements
the CompositeReader
interface, it is not possible to directly get postings.
Concrete subclasses of IndexReader are usually constructed with a call to
one of the static open()
methods, e.g. DirectoryReader.open(Directory)
.
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.
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader
IndexReader.ReaderClosedListener
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionfinal CompositeReaderContext
Expert: Returns the rootIndexReaderContext
for thisIndexReader
's sub-reader tree.protected abstract List<? extends IndexReader>
Expert: returns the sequential sub readers that this reader is logically composed of.toString()
Methods inherited from class org.apache.lucene.index.IndexReader
addReaderClosedListener, close, decRef, docFreq, doClose, document, document, document, ensureOpen, equals, getCombinedCoreAndDeletesKey, getCoreCacheKey, getDocCount, getRefCount, getSumDocFreq, getSumTotalTermFreq, getTermVector, getTermVectors, hasDeletions, hashCode, incRef, leaves, maxDoc, numDeletedDocs, numDocs, open, open, open, open, open, registerParentReader, removeReaderClosedListener, totalTermFreq, tryIncRef
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Constructor Details
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CompositeReader
protected CompositeReader()Sole constructor. (For invocation by subclass constructors, typically implicit.)
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Method Details
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toString
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getSequentialSubReaders
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()
.- See Also:
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getContext
Description copied from class:IndexReader
Expert: Returns the rootIndexReaderContext
for thisIndexReader
'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 anAtomicReaderContext
.Note: Any of the sub-
CompositeReaderContext
instances referenced from this top-level context do not supportCompositeReaderContext.leaves()
. Only the top-level context maintains the convenience leaf-view for performance reasons.- Specified by:
getContext
in classIndexReader
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