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https://issues.apache.org/jira/browse/FLINK-15004?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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godfrey he updated FLINK-15004:
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Summary: Choose two-phase Aggregate if the statistics is unknown (was:
Choose SortMergeJoin instead of HashJoin if the statistics is unknown)
> Choose two-phase Aggregate 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: 1.9.0, 1.9.1
> Reporter: godfrey he
> Assignee: godfrey he
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.10.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> 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 of {{HashJoin}} has huge input size. So It's
> better to use {{SortMergeJoin}} for execution stability if the statistics is
> unknown.
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