[jira] [Comment Edited] (CALCITE-2343) PushProjector with OVER expression causing infinite loop

["Vladimir Sitnikov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-2343?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16736983#comment-16736983 ] 

Vladimir Sitnikov edited comment on CALCITE-2343 at 1/8/19 10:35 AM:
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I've looked into the issue, and I disagree with the analysis.

Technically speaking, RexOver must not be pushed into JOIN / UNION / FILTER since it might produce wrong result.
However, if RexOver is using just a single field, then Project(Union(T), expr=count($0) over ()) could be transformed into Project(Union(Project(T, $0)), expr=count($0) over ()).  In other words, it could trim the set of required columns.

However, I don't quite get the logic of PushProjector / preserveExprCondition.

[~laurentgo] would you please look into the issue one more time and update the PR?


was (Author: vladimirsitnikov):
I've looked into the issue, and I disagree with the analysis.

Technically speaking, RexOver must not be pushed into JOIN / UNION / FILTER since it might produce wrong result.
However, if RexOver is using just a single field, then Project(Union(x), expr=count($0) over ()) could be transformed into Project(Union(Project(x, $0)), expr=count($0) over ()).  In other words, it could trim the set of required columns.

However, I don't quite get the logic of PushProjector / preserveExprCondition.

[~laurentgo] would you please look into the issue one more time and update the PR?

> PushProjector with OVER expression causing infinite loop
> --------------------------------------------------------
>
>                 Key: CALCITE-2343
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2343
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Laurent Goujon
>            Assignee: Laurent Goujon
>            Priority: Major
>
> When applying the {{ProjectJoinTransposeRule}} on a project with a Rex expression containing a RexOver call (using HepPlanner), this might cause an infinite loop (and ultimately a StackOverflowError exception) as PushProjector identify the RexOver call as to be push down under the join, but doesn't not rewrite correctly the top Project expression. 



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