[jira] [Commented] (CALCITE-1990) Make RelDistribution to extends RelMultipleTrait

["Julian Hyde (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-1990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16239318#comment-16239318 ] 

Julian Hyde commented on CALCITE-1990:
--------------------------------------

Reviewing and testing https://github.com/apache/calcite/pull/541/commits/fed879b3f2cdea53d742b90786407328a3a49f02 now. I will commit when tests pass.

I added {{RelDistributionTest}} to {{CalciteSuite}}, and changed your {{compareTo}} method to use guava's {{Ordering.lexicographical()}}.

> Make RelDistribution to extends RelMultipleTrait
> ------------------------------------------------
>
>                 Key: CALCITE-1990
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1990
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: LeoWangLZ
>            Assignee: Julian Hyde
>   Original Estimate: 0.2h
>  Remaining Estimate: 0.2h
>
> In Distributed System, RelDistribution is used for Exchange or SortExchange. for some operators it may deliver RelDistribution Trait, but some operator like SortedMergeJoin may deliver multiple traits.
> eg:
> {code:java}
> Query:
> select * from T1 join T2 on T1.c1=T2.d1;
> Suppose Plan:
> SortedMergeJoin
>     Exchange(c1)
>         T1(c1)
>     Exchange(d1)
>         T2(d1)
> {code}
> than SortedMergeJoin can deliver RelDistribution(hash\[c1\]) or RelDistribution(hash\[d1\]).
> we can consider RelDistribution extend RelMultipleTrait like RelCollation. 
> EnumerableMergeJoin is the case for RelCollation, and RelDistribution is also fit for SortedMergeJoin in Distributed system



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