Mailing List Archive

[ANNOUNCE] Apache Lucene 6.4.0 released
23 January 2017, Apache Luceneā„¢ 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

This release contains numerous bug fixes, optimizations, and
improvements, some of which are highlighted below. The release is
available for immediate download at:

Lucene 6.4.0 Release Highlights:

New features
* 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
* 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

Along with numerous bug fixes.

Further details of changes are available in the change log available at:

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 (

Note: The Apache Software Foundation uses an extensive mirroring network
for distributing releases. It is possible that the mirror you are using may
not have replicated the release yet. If that is the case, please try
another mirror. This also applies to Maven access.

Jim Ferenczi