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https://issues.apache.org/jira/browse/DRILL-6400?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kunal Khatua updated DRILL-6400:
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Fix Version/s: Future
> Hash-Aggr: Avoid recreating common Hash-Table setups for every partition
> ------------------------------------------------------------------------
>
> Key: DRILL-6400
> URL: https://issues.apache.org/jira/browse/DRILL-6400
> Project: Apache Drill
> Issue Type: Improvement
> Components: Execution - Relational Operators
> Affects Versions: 1.13.0
> Reporter: Boaz Ben-Zvi
> Assignee: Boaz Ben-Zvi
> Priority: Minor
> Fix For: Future
>
>
> The current Hash-Aggr code (and soon the Hash-Join code) creates multiple
> partitions to hold the incoming data; each partition with its own HashTable.
> The current code invokes the HashTable method
> _createAndSetupHashTable()_ for *each* partition. But most of the setups done
> by this method are identical for all the partitions (e.g., code generation).
> Calling this method has a performance cost (some local tests measured between
> 3 - 30 milliseconds, depends on the key columns).
> Suggested performance improvement: Extract the common settings to be called
> *once*, and use the results later by all the partitions. When running with
> the default 32 partitions, this can have a measurable improvement (and if
> spilling, this method is used again....).
>
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