[jira] [Commented] (CALCITE-4018) Implement trait propagation for EnumerableValues

["Rui Wang (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4018?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17112794#comment-17112794 ] 

Rui Wang commented on CALCITE-4018:
-----------------------------------

Could you clarify a bit on:

which code/implementation/mechanism make Values "it will enumerate all the possible collations"? It sounds like somewhere must have a for loop to go through all columns in Values, have a collation on each column and add more options to search space? 

>  Implement trait propagation for EnumerableValues
> -------------------------------------------------
>
>                 Key: CALCITE-4018
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4018
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>            Reporter: Haisheng Yuan
>            Priority: Major
>
> Only passThrough is needed.
> Currently, when Values is created, it will enumerate all the possible collations no matter parent operator requires it or not, it will be a disaster if the Values has thousands of columns, and the parent operator may be just a hash aggregate or hashjoin, which doesn't care about its collation.
> The collation should be created on demand by calling passThrough.



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