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https://issues.apache.org/jira/browse/FLINK-12173?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17872447#comment-17872447
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Jim Hughes commented on FLINK-12173:
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[~jark] This looks like a neat optimization. Would the approach be to write an
optimizer rule?
If so, are there any corner cases to consider? Generally, I can imagine
optimization rules firing in inappropriate situations and causing trouble.
> Optimize "SELECT DISTINCT" into Deduplicate with keep first row
> ---------------------------------------------------------------
>
> Key: FLINK-12173
> URL: https://issues.apache.org/jira/browse/FLINK-12173
> Project: Flink
> Issue Type: New Feature
> Components: Table SQL / Planner
> Reporter: Jark Wu
> Priority: Major
> Labels: auto-deprioritized-major, auto-deprioritized-minor
>
> The following distinct query can be optimized into deduplicate on keys "a, b,
> c, d" and keep the first row.
> {code:sql}
> SELECT DISTINCT a, b, c, d;
> {code}
> We can optimize this query into Deduplicate to get a better performance than
> GroupAggregate.
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