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Posted to issues-all@impala.apache.org by "Fucun Chu (Jira)" <ji...@apache.org> on 2020/11/11 12:42:00 UTC

[jira] [Created] (IMPALA-10317) Add query option that limits join #rows at runtime

Fucun Chu created IMPALA-10317:
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             Summary: Add query option that limits join #rows at runtime
                 Key: IMPALA-10317
                 URL: https://issues.apache.org/jira/browse/IMPALA-10317
             Project: IMPALA
          Issue Type: New Feature
          Components: Backend
            Reporter: Fucun Chu
            Assignee: Fucun Chu
         Attachments: query82_summary.png

Reject queries that rows produced too bigger by join operator when executing the query.
This is a mechanism to protect the cluster from potentially harmful queries.

When the cardinality of the table is very large and the join conditions are very bad, the number of rows produced by the join will be very large, sometimes tens of billions, which affects the cluster status and other running queries.

In our environment, the NUM_JOIN_ROWS_PRODUCED_LIMIT query option is added to limit the number of rows produced by a single join operator.
Implementation refers to [IMPALA-6034|https://issues.apache.org/jira/browse/IMPALA-6034] and summary (see the figure below), check the join operator #rows size



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