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Posted to issues@calcite.apache.org by "Stamatis Zampetakis (JIRA)" <ji...@apache.org> on 2018/09/12 15:11:00 UTC

[jira] [Commented] (CALCITE-2554) Enrich EnumerableJoin opetaror with order preserving information

    [ https://issues.apache.org/jira/browse/CALCITE-2554?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16612301#comment-16612301 ] 

Stamatis Zampetakis commented on CALCITE-2554:
----------------------------------------------

I propose to adapt the EnumerableJoinRule so that it retains the RelCollation trait from the left input and add a few tests over org.apache.calcite.linq4j.EnumerableDefaults#join_ which verify that the order of the left input remains intact.

> Enrich EnumerableJoin opetaror with order preserving information
> ----------------------------------------------------------------
>
>                 Key: CALCITE-2554
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2554
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.17.0
>            Reporter: Stamatis Zampetakis
>            Assignee: Julian Hyde
>            Priority: Minor
>             Fix For: 1.18.0
>
>
> The EnumerableJoin operator is backed up by a join algorithm (org.apache.calcite.linq4j.EnumerableDefaults#join_) which preserves the order of the left (outer) input. However, this information is not reflected in the RelTraitSet and thus cannot be exploited by the optimizer. Without this information, sort operators following the join cannot be removed (using SortRemoveRule) leading to suboptimal plans.
>  



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