[
https://issues.apache.org/jira/browse/IMPALA-10317?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17231124#comment-17231124
]
Fucun Chu commented on IMPALA-10317:
------------------------------------
Regarding judging that a join is hugely expanding,it is necessary to consider
the join type, distribution mode, table size, growth rate, etc. to prevent
misjudgments. An estimation model may be required, which will be iterated in
the next version. Welcome to provide relevant information.
Our experience is that the threshold is calculated based on the query history,
combined with query duration, available memory, and concurrency. In practice,
the SCAN_BYTES_LIMIT option will be combined to prevent potentially harmful
queries.
> 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
> Priority: Major
> 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
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
