[jira] [Resolved] (CALCITE-4097) Avoid requesting unnecessary trait request when deriving traits from child inputs

["Haisheng Yuan (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-4097?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Haisheng Yuan resolved CALCITE-4097.
------------------------------------
    Fix Version/s: 1.24.0
       Resolution: Fixed

Fixed in [https://github.com/apache/calcite/commit/640da7c6d85c3e83fe38fb45d7f23ef5e1000c4e].

> Avoid requesting unnecessary trait request when deriving traits from child inputs
> ---------------------------------------------------------------------------------
>
>                 Key: CALCITE-4097
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4097
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>            Reporter: Haisheng Yuan
>            Priority: Major
>             Fix For: 1.24.0
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> If the child subset is used to derive new traits for
> current relnode, the subset will be marked REQUIRED
> when registering the new derived relnode and later
> will add enforcers between other delivered subsets.
> e.g. a MergeJoin request both inputs hash distributed
> by [a,b] sorted by [a,b]. If the left input R1 happens to
> be distributed by [a], the MergeJoin can derive new
> traits from this input and request both input to be
> distributed by [a] sorted by [a,b]. In case there is a
> alternative R2 with ANY distribution in the left input's
> RelSet, we end up with requesting hash distribution
> [a] on alternative R2, which is unnecessary and waste,
> because we request distribution by [a] because of R1 can
> deliver the exact same distribution and we don't need to
> enforce properties on other subsets that can't satisfy
> the specific trait requirement.



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