Title: Apache Lucene™ 9.0.0 available category: core/news URL: save_as:

The Lucene PMC is pleased to announce the release of Apache Lucene 9.0.0.

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 bug fixes, 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 9.0.0 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.

Please read CHANGES.txt for a full list of new features and changes:

https://lucene.apache.org/core/9_0_0/changes/Changes.html