org.apache.lucene.index

Class ParallelCompositeReader

java.lang.Object

org.apache.lucene.index.IndexReader

org.apache.lucene.index.CompositeReader

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

org.apache.lucene.index.ParallelCompositeReader

All Implemented Interfaces:

Closeable, AutoCloseable

public class ParallelCompositeReader
extends BaseCompositeReader<LeafReader>

An 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.

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

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

Modifier and Type	Method and Description
protected void	doClose() Implements close.
IndexReader.CacheHelper	getReaderCacheHelper() Optional method: Return a IndexReader.CacheHelper that 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, totalTermFreq

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

getContext, toString

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

close, decRef, document, document, ensureOpen, equals, getRefCount, getTermVector, hasDeletions, hashCode, incRef, leaves, numDeletedDocs, registerParentReader, 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

getReaderCacheHelper

public IndexReader.CacheHelper getReaderCacheHelper()

Description copied from class: IndexReader

Optional method: Return a IndexReader.CacheHelper that 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 null indicates 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:

getReaderCacheHelper in class IndexReader

doClose

protected void doClose()
                throws IOException

Description copied from class: IndexReader

Implements close.

Specified by:

doClose in class IndexReader

Throws:

IOException