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https://issues.apache.org/jira/browse/CALCITE-5715?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benchao Li updated CALCITE-5715:
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Description:
We already have many similar usages (prune old nodes when the new one is
obviously better, e.g. in
[CalcMergeRule|https://github.com/apache/calcite/blob/c56d5564628de6b3265f960764a6f6fc43935a75/core/src/main/java/org/apache/calcite/rel/rules/CalcMergeRule.java#L85-L90]
to reduce the search scope, I propose to also add this for
{{ProjectMergeRule}}. Do you have any concerns about this?
In {{ProjectMergeRule}}, there is a case that after merging the two
{{Project}}, we'll find the new Project is trivial and we'll transform to the
bottomProject's
input(https://github.com/apache/calcite/blob/c56d5564628de6b3265f960764a6f6fc43935a75/core/src/main/java/org/apache/calcite/rel/rules/ProjectMergeRule.java#L132-L139).
In this case, both topProject and bottomProject could be pruned?
The reason I propose to do this optimization for {{ProjectMergeRule}} is that I
met a problem that two sets will point to each other after projection merging,
and the planner will run into dead loop. (It's hard to show the details, I
haven't got a simple reproducible demo yet)
was:
We already have many similar usages (prune old nodes) to reduce the search
scope, I propose to also add this for {{ProjectMergeRule}}. Do you have any
concerns about this?
The reason I propose to do this optimization for {{ProjectMergeRule}} is that I
met a problem that two sets will point to each other after projection merging,
and the planner will run into dead loop. (It's hard to show the details, I
haven't got a simple reproducible demo yet)
> Prune old nodes after projection merging in ProjectMergeRule
> ------------------------------------------------------------
>
> Key: CALCITE-5715
> URL: https://issues.apache.org/jira/browse/CALCITE-5715
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.34.0
> Reporter: Benchao Li
> Priority: Major
>
> We already have many similar usages (prune old nodes when the new one is
> obviously better, e.g. in
> [CalcMergeRule|https://github.com/apache/calcite/blob/c56d5564628de6b3265f960764a6f6fc43935a75/core/src/main/java/org/apache/calcite/rel/rules/CalcMergeRule.java#L85-L90]
> to reduce the search scope, I propose to also add this for
> {{ProjectMergeRule}}. Do you have any concerns about this?
> In {{ProjectMergeRule}}, there is a case that after merging the two
> {{Project}}, we'll find the new Project is trivial and we'll transform to the
> bottomProject's
> input(https://github.com/apache/calcite/blob/c56d5564628de6b3265f960764a6f6fc43935a75/core/src/main/java/org/apache/calcite/rel/rules/ProjectMergeRule.java#L132-L139).
> In this case, both topProject and bottomProject could be pruned?
> The reason I propose to do this optimization for {{ProjectMergeRule}} is that
> I met a problem that two sets will point to each other after projection
> merging, and the planner will run into dead loop. (It's hard to show the
> details, I haven't got a simple reproducible demo yet)
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