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https://issues.apache.org/jira/browse/FLINK-10474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16644688#comment-16644688
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Fabian Hueske commented on FLINK-10474:
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Hmm, OK. I had a closer look at the PR.
The rules don't seem to be too complex and are applied in the normalization
phase, i.e., do not interact with most of the other rewrite rules. In essence
it's a expression transformation similar to \{{ReduceExpressionsRule}}. I'd
compose the rules a bit differently, but that's a minor issue (will leave a
comment on the PR).
I think the solution is good.
> Don't translate IN with Literals 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
> Labels: pull-request-available
>
> IN predicates with literals 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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