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Posted to issues@flink.apache.org by "Rong Rong (JIRA)" <ji...@apache.org> on 2018/10/02 03:03:00 UTC
[jira] [Commented] (FLINK-10474) Don't translate IN to JOIN with
VALUES for streaming queries
[ https://issues.apache.org/jira/browse/FLINK-10474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16634867#comment-16634867 ]
Rong Rong commented on FLINK-10474:
-----------------------------------
Voting for the first approach.
I was actually wondering. Is there benefit from translating the IN to JOIN operator (even on batch side) if the operand after IN is statically defined.
> Don't translate IN to JOIN with VALUES for streaming queries
> ------------------------------------------------------------
>
> Key: FLINK-10474
> URL: https://issues.apache.org/jira/browse/FLINK-10474
> Project: Flink
> Issue Type: Improvement
> Components: Table API & SQL
> Affects Versions: 1.6.1, 1.7.0
> Reporter: Fabian Hueske
> Assignee: Hequn Cheng
> Priority: Major
>
> IN clauses are translated to JOIN with VALUES if the number of elements in the IN clause exceeds a certain threshold. This should not be done, because a streaming join is very heavy and materializes both inputs (which is fine for the VALUES) input but not for the other.
> There are two ways to solve this:
> # don't translate IN to a JOIN at all
> # translate it to a JOIN but have a special join strategy if one input is bound and final (non-updating)
> Option 1. should be easy to do, option 2. requires much more effort.
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