public class ParallelCompositeReader extends BaseCompositeReader<LeafReader>
CompositeReaderwhich 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
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
it might happen that the segment structure of your index is no longer predictable.
|Constructor and Description|
Create a ParallelCompositeReader based on the provided readers.
Expert: create a ParallelCompositeReader based on the provided readers and storedFieldReaders; when a document is loaded, only storedFieldsReaders will be used.
Create a ParallelCompositeReader based on the provided readers; auto-closes the given readers on
|Modifier and Type||Method and Description|
Optional method: Return a
docFreq, document, getDocCount, getSequentialSubReaders, getSumDocFreq, getSumTotalTermFreq, getTermVectors, maxDoc, numDocs, readerBase, readerIndex, totalTermFreq
close, decRef, document, document, ensureOpen, equals, getRefCount, getTermVector, hasDeletions, hashCode, incRef, leaves, numDeletedDocs, registerParentReader, tryIncRef
public ParallelCompositeReader(CompositeReader... readers) throws IOException
public ParallelCompositeReader(boolean closeSubReaders, CompositeReader... readers) throws IOException
public ParallelCompositeReader(boolean closeSubReaders, CompositeReader readers, CompositeReader storedFieldReaders) throws IOException
public IndexReader.CacheHelper getReaderCacheHelper()
IndexReader.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
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.
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