Class ParallelCompositeReader
- All Implemented Interfaces:
Closeable,AutoCloseable
CompositeReader which reads multiple, parallel indexes. Each index added must have the
same number of documents, and exactly the same number of leaves (with equal maxDoc), but
typically each contains different fields. Deletions are taken from the first reader. Each
document contains the union of the fields of all documents with the same document number. When
searching, matches for a query term are from the first index added that has the field.
This is useful, e.g., with collections that have large fields which change rarely and small fields that change more frequently. The smaller fields may be re-indexed in a new index and both indexes may be searched together.
Warning: It is up to you to make sure all indexes are created and modified
the same way. For example, if you add documents to one index, you need to add the same documents
in the same order to the other indexes. Failure to do so will result in undefined
behavior. A good strategy to create suitable indexes with IndexWriter is to use
LogDocMergePolicy, as this one does not reorder documents during merging (like
TieredMergePolicy) and triggers merges by number of documents per segment. If you use different
MergePolicys it might happen that the segment structure of your index is no longer
predictable.
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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
ConstructorsConstructorDescriptionParallelCompositeReader(boolean closeSubReaders, CompositeReader... readers) Create a ParallelCompositeReader based on the provided readers.ParallelCompositeReader(boolean closeSubReaders, CompositeReader[] readers, CompositeReader[] storedFieldReaders) Expert: create a ParallelCompositeReader based on the provided readers and storedFieldReaders; when a document is loaded, only storedFieldsReaders will be used.ParallelCompositeReader(CompositeReader... readers) Create a ParallelCompositeReader based on the provided readers; auto-closes the given readers onIndexReader.close(). -
Method Summary
Modifier and TypeMethodDescriptionprotected voiddoClose()Implements close.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, getDocCount, getSequentialSubReaders, getSumDocFreq, getSumTotalTermFreq, maxDoc, numDocs, readerBase, readerIndex, storedFields, termVectors, totalTermFreqMethods inherited from class org.apache.lucene.index.CompositeReader
getContext, toStringMethods inherited from class org.apache.lucene.index.IndexReader
close, decRef, ensureOpen, equals, getRefCount, hasDeletions, hashCode, incRef, leaves, notifyReaderClosedListeners, numDeletedDocs, registerParentReader, tryIncRef
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Constructor Details
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ParallelCompositeReader
Create a ParallelCompositeReader based on the provided readers; auto-closes the given readers onIndexReader.close().- Throws:
IOException
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ParallelCompositeReader
public ParallelCompositeReader(boolean closeSubReaders, CompositeReader... readers) throws IOException Create a ParallelCompositeReader based on the provided readers.- Throws:
IOException
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ParallelCompositeReader
public ParallelCompositeReader(boolean closeSubReaders, CompositeReader[] readers, CompositeReader[] storedFieldReaders) throws IOException Expert: create a ParallelCompositeReader based on the provided readers and storedFieldReaders; when a document is loaded, only storedFieldsReaders will be used.- Throws:
IOException
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Method Details
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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
Description copied from class:IndexReaderImplements close.- Specified by:
doClosein classIndexReader- Throws:
IOException
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