Page History

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This patch release contains bug fixes that are highlighted below. The release is available for immediate download at:

Lucene 9.

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API Changes

Make TaskExecutor constructor public and use TaskExecutor for concurrent HNSW graph build. (Shubham Chaudhary)

New Features

Add int8 scalar quantization to the HNSW vector format. This optionally allows for more compact lossy storage for the vectors, requiring about 75% approximately 4x less memory for fast HNSW search.
HNSW graph now can be merged with multiple

thread

threads, leveraging the same infrastructure that inter-segment concurrency utilizes.

Improvements

Create a TaskExecutor when an executor is not provided to the IndexSearcher, in order to simplify consumer's code
Speed up Panama vector support, use FMA, and test improvements.
FSTCompiler can now approximately limit how much RAM it uses to share suffixes share suffixes during FST construction using the suffixRAMLimitMB method.

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Faster top-level conjunctions on term queries when sorting by descending score.
Change Postings back to using FOR in Lucene99PostingsFormat. Freqs, positions and offset keep using PFOR.

... plus a multitude of helpful bug fixes!

Further details of changes are available in the change log available at: http://lucene.apache.org/core/9_9_0/changes/Changes.html.

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

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