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Posted to dev@hive.apache.org by "Remus Rusanu (JIRA)" <ji...@apache.org> on 2017/05/30 19:21:05 UTC

[jira] [Created] (HIVE-16790) HiveCostModel.JoinAlgorithm and derivatives abuse RelMetadataQuery.instance

Remus Rusanu created HIVE-16790:
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             Summary: 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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