[jira] [Resolved] (CALCITE-7053) In HepPlanner, move down the collectGarbage to topological order for better optimizer performance

["xiong duan (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-7053?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

xiong duan resolved CALCITE-7053.
---------------------------------
    Fix Version/s: 1.41.0
         Assignee: xiong duan
       Resolution: Fixed

> In HepPlanner, move down the collectGarbage to topological order for better optimizer performance
> -------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-7053
>                 URL: https://issues.apache.org/jira/browse/CALCITE-7053
>             Project: Calcite
>          Issue Type: Improvement
>            Reporter: xiong duan
>            Assignee: xiong duan
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.41.0
>
>
> According to the java comment in HepPlanner#getGraphIterator:
> {code:java}
>     // Make sure there's no garbage, because topological sort
>     // doesn't start from a specific root, and rules can't
>     // deal with firing on garbage.
>     // FIXME jvs 25-Sept-2006:  I had to move this earlier because
>     // of FRG-215, which is still under investigation.  Once we
>     // figure that one out, move down to location below for
>     // better optimizer performance.
> {code}
> Based on the current implementation, I haven't found the reason why the depth-first order requires garbage collection every time. Since it always starts the search from a specific
> Vertex, the issue mentioned the FRG-215 -
>  I haven't found any description or information about this problem. Therefore, this PR attempts to delegate the collectGarbage operation to the topological order.



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