org.apache.lucene.index
Class ParallelCompositeReader

java.lang.Object
  extended by org.apache.lucene.index.IndexReader
      extended by org.apache.lucene.index.CompositeReader
          extended by org.apache.lucene.index.BaseCompositeReader<IndexReader>
              extended by org.apache.lucene.index.ParallelCompositeReader
All Implemented Interfaces:
Closeable

public 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
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
protected  void doClose()
          Implements close.
 
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
addReaderClosedListener, close, decRef, document, document, ensureOpen, equals, getCombinedCoreAndDeletesKey, getCoreCacheKey, getRefCount, getTermVector, hasDeletions, 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

doClose

protected void doClose()
                throws IOException
Description copied from class: IndexReader
Implements close.

Specified by:
doClose in class IndexReader
Throws:
IOException


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