Mailing List Archive

[ANNOUNCE] Apache Lucene 9.0.0 released
The Lucene PMC is pleased to announce the release of Apache Lucene 9.0.

Apache Lucene is a high-performance, full-featured search engine
library written entirely in Java. It is a technology suitable for
nearly any application that requires structured search, full-text
search, faceting, nearest-neighbor search across high-dimensionality
vectors, spell correction or query suggestions.

This release contains numerous features, optimizations, and
improvements, some of which are highlighted below. The release is
available for immediate download at:
https://lucene.apache.org/core/downloads.html

Lucene 9.0 Release Highlights

System requirements
- Lucene 9.0 requires JDK 11 or newer

New features
- Support for indexing high-dimensionality numeric vectors to perform
nearest-neighbor search, using the Hierarchical Navigable Small World
graph algorithm
- New Analyzers for Serbian, Nepali, and Tamil languages
- IME-friendly autosuggest for Japanese
- Snowball 2, adding Hindi, Indonesian, Nepali, Serbian, Tamil, and
Yiddish stemmers
- New normalization/stemming for Swedish and Norwegian

Optimizations
- Up to 400% faster taxonomy faceting
- 10-15% faster indexing of multi-dimensional points
- Several times faster sorting on fields that are indexed with
points. This optimization used to be an opt-in in late 8.x releases
and is now opt-out as of 9.0.
- ConcurrentMergeScheduler now assumes fast I/O, likely improving
indexing speed in case where heuristics would incorrectly detect
whether the system had modern I/O or not
- Encoding of postings lists changed from FOR-delta to PFOR-delta to
save further disk space

Other
- File formats have all been changed from big-endian order to little
endian order
- Lucene 9 no longer has split packages. This required renaming some
packages outside of the lucene-core JAR, so you will need to adjust
some imports accordingly.
- Using Lucene 9 with the module system should be considered
experimental. We expect to make progress on this in future 9.x
releases.

Further details of changes are available in the change log available at:
http://lucene.apache.org/core/9_0_0/changes/Changes.html
and the migration guide available at:
https://lucene.apache.org/core/9_0_0/MIGRATE.html

Please report any feedback to the mailing lists
(http://lucene.apache.org/core/discussion.html)

--
Adrien

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