org.apache.lucene.index

Class ParallelCompositeReader

java.lang.Object

org.apache.lucene.index.IndexReader

org.apache.lucene.index.CompositeReader

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

org.apache.lucene.index.ParallelCompositeReader

All Implemented Interfaces:

Closeable

public final class ParallelCompositeReader
extends BaseCompositeReader<IndexReader>

An CompositeReader which reads multiple, parallel indexes. Each index added must have the same number of documents, and exactly the same hierarchical subreader structure, 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.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader

IndexReader.ReaderClosedListener

Constructor Summary

Constructors

Constructor and Description
ParallelCompositeReader(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 on IndexReader.close().

Method Summary

Methods

Modifier and Type	Method and Description
protected void	doClose() Implements close.
String	toString()

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

docFreq, document, getSequentialSubReaders, getTermVectors, hasDeletions, maxDoc, numDocs, readerBase, readerIndex, totalTermFreq

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

getContext

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

addReaderClosedListener, close, decRef, document, document, ensureOpen, equals, getCombinedCoreAndDeletesKey, getCoreCacheKey, getRefCount, getTermVector, hashCode, incRef, leaves, numDeletedDocs, open, open, open, open, open, registerParentReader, removeReaderClosedListener, tryIncRef

Methods inherited from class java.lang.Object

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

Constructor Detail

ParallelCompositeReader

public ParallelCompositeReader(CompositeReader... readers)
                        throws IOException

Create a ParallelCompositeReader based on the provided readers; auto-closes the given readers on IndexReader.close().

Throws:

IOException

ParallelCompositeReader

public ParallelCompositeReader(boolean closeSubReaders,
                       CompositeReader... readers)
                        throws IOException

Create a ParallelCompositeReader based on the provided readers.

Throws:

IOException

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

Method Detail

toString

public String toString()

Overrides:

toString in class CompositeReader

doClose

protected void doClose()
                throws IOException

Description copied from class: IndexReader

Implements close.

Specified by:

doClose in class IndexReader

Throws:

IOException