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Posted to issues@flink.apache.org by "Lyn Zhang (Jira)" <ji...@apache.org> on 2021/10/26 11:11:00 UTC
[jira] [Commented] (FLINK-24610) Flink projection common expression
elimination
[ https://issues.apache.org/jira/browse/FLINK-24610?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17434275#comment-17434275 ]
Lyn Zhang commented on FLINK-24610:
-----------------------------------
[~jark] Please help to review this issue if you are free
> Flink projection common expression elimination
> ----------------------------------------------
>
> Key: FLINK-24610
> URL: https://issues.apache.org/jira/browse/FLINK-24610
> Project: Flink
> Issue Type: Improvement
> Components: Table SQL / Planner
> Reporter: Lyn Zhang
> Priority: Major
> Labels: pull-request-available
>
> Flink sql projection not support reusing common expression in code generator.
> For example the sql: SELECT split(a, '_'_)[1], split(a, '_'_)[2] FROM table.The function split(a, '_') will be invoked 2 times per row data.
> We can use CalcProgram.getExprList to generator each expression and CalcProgram.getProjectList to eliminate common expression.
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