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https://issues.apache.org/jira/browse/HIVE-29121?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated HIVE-29121:
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Labels: pull-request-available (was: )
> Restore HiveSubQueryRemoveRule to use InnerJoin instead of SemiJoin for
> uncorrelated IN/EXISTS subqueries with RelOptUtil.Logic.TRUE.
> -------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-29121
> URL: https://issues.apache.org/jira/browse/HIVE-29121
> Project: Hive
> Issue Type: Improvement
> Environment: [^plan.example.txt]
> Reporter: Seonggon Namgung
> Assignee: Seonggon Namgung
> Priority: Major
> Labels: pull-request-available
> Attachments: plan.example.txt
>
>
> This JIRA is an addendum patch to HIVE-24685 and aims to restore the compiler
> logic from HIVE-17767.
> During the substitution of HiveSubQRemoveRelBuilder with Calcite's RelBuilder
> in HIVE-24685, Hive was changed to always use SemiJoin when handling
> uncorrelated IN/EXISTS subqueries with logic == RelOptUtil.Logic.TRUE. Since
> the SemiJoin is intended for use with correlated IN/EXISTS subqueries in
> conjunction with AGGR removal (cf. HIVE-17767), we should avoid using
> SemiJoin for the uncorrelated case, which neither benefits from AGGR removal
> nor allows the application of rules that cannot handle HiveSemiJoin (e.g.,
> join reordering).
> For clarity, the following combinations of query plans are attached. From the
> attached plans, we can observe that HIVE-24685 introduces a SemiJoin without
> removing HiveAggregate, unlike HIVE-17767.
> The attached plans cover the following combinations:
> * {Before HIVE-17767, After HIVE-17767, After HIVE-24685}
> * {Correlated, Uncorrelated}
> * {Before subquery removal, After subquery removal, After decorrelation}
> We discovered this issue while investigating a performance regression in
> TPC-DS Query 23.
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