Title: Apache Lucene™ 6.4.0 available category: core/news URL: save_as:

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:

https://www.apache.org/dyn/closer.lua/lucene/java/6.4.0

See the CHANGES.txt file included with the release for a full list of changes and further details.

Highlights of this Lucene release include:

  • 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

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.