23 January 2017, Apache Lucene™ 6.4.0 available The Lucene PMC is pleased to announce the release of Apache Lucene 6.4.0.
Apache Lucene is a high-performance, full-featured text search engine library written entirely in Java. It is a technology suitable for nearly any application that requires full-text search, especially cross-platform.
This release contains numerous bug fixes, optimizations, and improvements, some of which are highlighted below. The release is available for immediate download at:
Please read CHANGES.txt for a full list of new features and changes:
Lucene 6.4.0 Release Highlights:
- Lucene's best efforts to un-map memory mapped files with "MMapDirectory" now work with the latest Java9 early access builds
A new similarity "BooleanSimilarity" that gives terms a score that is equal to their query boost
The axiomatic family of similarities (6 in total) based on https://www.eecis.udel.edu/~hfang/pubs/sigir05-axiom.pdf
A new token filter "SynonymGraphFilter" that outputs a correct graph structure for multi-token synonyms at query time
Graph token streams, such as those produced by the "SynonymGraphFilter", are now handled accurately by query parsers
A new collector "DocValuesStatsCollector" gives the ability to compute statistics on DocValues field
It is now possible to filter "SortedDocValues" and "SortedSetDocValues" terms enum with a compiled automaton
The "UnifiedHighlighter" can now highlight fields with queries that don't necessarily refer to that field
DrillSideways can now run queries concurrently
- Index sorting now supports sorting on multi-valued fields using MIN, MAX, etc. selectors
Points do not store the implicit split dimension in the 1-dimension case. This saves between 6% memory for the largest types such an InetAddressPoint to 33% for the smaller types such as HalfFloatPoint.
- The BKD in-memory index for dimensional points now uses a compressed format, using substantially less RAM in some cases
- The BKD writing now buffers each leaf block in heap before writing to disk, giving a small speedup in points-heavy use cases
"TermAutomatonQuery" now rewrites to more efficient queries when possible
Along with numerous bug fixes.
Further details of changes are available in the change log available at: http://lucene.apache.org/core/6_4_0/changes/Changes.html
Please note, this release cannot be built from source with Java 8 update 121, use an earlier version instead! This is caused by a bug introduced into the Javadocs tool shipped with that update. The workaround was too late for this Lucene release. Of course, you can use the binary artifacts.
Please report any feedback to the mailing lists (http://lucene.apache.org/core/discussion.html)
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