perf(sql): statistics-based map pre-sizing for parallel group by #4517
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core/src/main/java/io/questdb/griffin/engine/table/AsyncGroupByAtom.java
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[PR Coverage check]😍 pass : 176 / 176 (100.00%) file detail
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bluestreak01
approved these changes
May 17, 2024
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The statistics are cached in the factory, so the factory must be reused on subsequent query execution to benefit from pre-sizing. The maps are now also allocated lazily on worker threads.
ClickBench result improvement:
The next step is to introduce a global cache of record cursor factories instead of the per-connection select query cache that we currently have. Will be done in a separate PR.