[jira] [Commented] (FLINK-10956) Reuse same rexCall during codegen

["Timo Walther (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-10956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16694593#comment-16694593 ] 

Timo Walther commented on FLINK-10956:
--------------------------------------

[~hequn8128] Yes, this is a known limitation that could be fixed by allowing "local references" in Calcite. Can you close this issue and maybe improve the description of the other issue? See FLINK-7403.

> Reuse same rexCall during codegen
> ---------------------------------
>
>                 Key: FLINK-10956
>                 URL: https://issues.apache.org/jira/browse/FLINK-10956
>             Project: Flink
>          Issue Type: Improvement
>            Reporter: Hequn Cheng
>            Assignee: Hequn Cheng
>            Priority: Major
>
> Currently, same rexCalls have not been reused during codegen. I think we can add some reuse logic to achieve a better performance. Take the following query as an example:
> {code:java}
> t.select(func0('c), func0('c), func0('c))
> {code}
> func0('c) is called three times for every input row even func0 is deterministic. It would be nice if we can reuse it. 
> Any suggestions are appreciated.



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