Introduce SwissTable-based hashing (LongSwissHash, BytesRefSwissHash) for ES|QL STATS#139343
Merged
ChrisHegarty merged 133 commits intoelastic:mainfrom Jan 6, 2026
Merged
Introduce SwissTable-based hashing (LongSwissHash, BytesRefSwissHash) for ES|QL STATS#139343ChrisHegarty merged 133 commits intoelastic:mainfrom
ChrisHegarty merged 133 commits intoelastic:mainfrom
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Buildkite benchmark this with clickbench please |
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Buildkite benchmark this with clickbench please |
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Buildkite benchmark this with esql please |
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This build ran two esql benchmarks to evaluate performance impact of this PR. History |
This was referenced Jan 13, 2026
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This PR introduces two new hash-table implementations - LongSwissHash and BytesRefSwissHash - as the first step in improving the performance and memory behavior of the ES|QL STATS operator. These structures are based on SwissTable-style open addressing with SIMD-friendly control bytes, offering significantly better probe behavior and cache locality than the current hash implementation.
A larger multi-step plan and follow-up work are tracked in the corresponding meta issue. #138799
What this PR includes
These structures form the foundation for replacing the STATS operator’s existing hash table with something faster, more predictable, and more memory-efficient under high cardinality. The implementation follows the same principles as SwissTable/Abseil, adapted for Elasticsearch’s memory model.
Contributors: @ChrisHegarty @nik9000 @MattAlp