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Posted to dev@flink.apache.org by "godfrey he (Jira)" <ji...@apache.org> on 2019/12/02 03:29:00 UTC

[jira] [Created] (FLINK-15004) Choose SortMergeJoin instead of HashJoin if the statistics is unknown

godfrey he created FLINK-15004:
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             Summary: Choose SortMergeJoin instead of HashJoin if the statistics is unknown
                 Key: FLINK-15004
                 URL: https://issues.apache.org/jira/browse/FLINK-15004
             Project: Flink
          Issue Type: Sub-task
          Components: Table SQL / Planner
    Affects Versions: 1.9.1, 1.9.0
            Reporter: godfrey he
             Fix For: 1.10.0


Currently, blink planner will use default rowCount value (defined in {{FlinkPreparingTableBase#DEFAULT_ROWCOUNT}} ) when the statistics is unknown, and maybe choose {{HashJoin}} instead of {{SortMergeJoin}}. The job will hang if the build side has huge input size. So It's better to use {{SortMergeJoin}} for execution stability if the statistics is unknown.



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