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https://issues.apache.org/jira/browse/HIVE-16790?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Remus Rusanu reassigned HIVE-16790:
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> HiveCostModel.JoinAlgorithm and derivatives abuse RelMetadataQuery.instance
> ---------------------------------------------------------------------------
>
> Key: HIVE-16790
> URL: https://issues.apache.org/jira/browse/HIVE-16790
> Project: Hive
> Issue Type: Bug
> Components: Query Planning
> Reporter: Remus Rusanu
> Assignee: Remus Rusanu
>
> Calling {{RelMetadataQuery.instance()}} has serious performance implication,
> as it invalidates the memoization cache used in Calcite, see HIVE-16757
> {{HiveCostModel.JoinAlgorithm}} and the derivate classes abuse this calls,
> sometimes multiple times per function. All methods in JoinAlgortihm that need
> a RelMetadataQuery should accept it as argument, not build one instance.
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