Pre-allocate capacity for definition & repetition levels#1
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theosib-amazon merged 1 commit intomasterfrom Mar 25, 2022
Merged
Pre-allocate capacity for definition & repetition levels#1theosib-amazon merged 1 commit intomasterfrom
theosib-amazon merged 1 commit intomasterfrom
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Testing shows 5% to 15% performance improvement on a lot of queries by pre-reserving capacity for definitionLevels and repetitionLevels.
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Testing shows 5% to 15% performance improvement on a lot of queries by pre-reserving capacity for definitionLevels and repetitionLevels.
Description
I did profiling on Trino while doing TPCDS queries from a Parquet source and noticed that a lot of them were wasting time on array copy while growing capacity of the definitionLevels and definitionLevels integer array lists. Pre-reserving capacity sped up a lot of queries, some as much as 15%.
Related issues, pull requests, and links
Performance optimization
Documentation
( ) No documentation is needed.
( ) Sufficient documentation is included in this PR.
( ) Documentation PR is available with #prnumber.
( ) Documentation issue #issuenumber is filed, and can be handled later.
Release notes
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( ) Release notes entries required with the following suggested text: