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https://issues.apache.org/jira/browse/IMPALA-12142?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Csaba Ringhofer resolved IMPALA-12142.
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Fix Version/s: Impala 4.3.0
Resolution: Fixed
> Default fetch_size of 10240 is suboptimal
> -----------------------------------------
>
> Key: IMPALA-12142
> URL: https://issues.apache.org/jira/browse/IMPALA-12142
> Project: IMPALA
> Issue Type: Improvement
> Components: Clients
> Reporter: Csaba Ringhofer
> Priority: Major
> Labels: performance
> Fix For: Impala 4.3.0
>
>
> While working on IMPALA-12138 it turned out that the default settings of
> batch_size=1024 and fetch_size=10240 are not ideal for the coordinator
> (RowMaterializationTimer). My guess for the cause is that HS2 results vectors
> are rounded up to power of 2 sizes leading to extra allocations and copying.
> query: select * from tpch_parquet.lineitem
> RowMaterializationTimer (before and after IMPALA-12138)
> fetch_size=10240: 3.6s ->3.2s
> fetch_size=8192: 2.8s->2.6s
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