[jira] [Commented] (FLINK-38793) Reuse result of functions if ther are used multiple times as input for other functions

["Sergey Nuyanzin (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-38793?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18083096#comment-18083096 ] 

Sergey Nuyanzin commented on FLINK-38793:
-----------------------------------------

Closing as it was fixed within FLINK-39268

> Reuse result of functions if ther are used multiple times as input for other functions
> --------------------------------------------------------------------------------------
>
>                 Key: FLINK-38793
>                 URL: https://issues.apache.org/jira/browse/FLINK-38793
>             Project: Flink
>          Issue Type: Bug
>            Reporter: Sergey Nuyanzin
>            Assignee: Sergey Nuyanzin
>            Priority: Major
>              Labels: pull-request-available
>
> An example
> {code:sql}
> SELECT LTRIM(q), RTRIM(q) FROM (SELECT TRIM(c) as q FROM MyTable) t
> {code}
> and plan shows
> {noformat}
>     <Resource name="optimized exec plan">
>       <![CDATA[
> Calc(select=[LTRIM(TRIM(BOTH, ' ', c)) AS EXPR$0, RTRIM(TRIM(BOTH, ' ', c)) AS EXPR$1])
> +- TableSourceScan(table=[[default_catalog, default_database, MyTable]], fields=[a, b, c])
> ]]>
>     </Resource>
> {noformat}
> which means {{TRIM(BOTH, ' ', c)}} here will be evaluated twice, in case of more usages like that it we be evaluated more times



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