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Posted to issues@calcite.apache.org by "Maryann Xue (JIRA)" <ji...@apache.org> on 2016/11/21 23:05:58 UTC

[jira] [Commented] (CALCITE-1498) RelMdUtil.checkInputForCollationAndLimit() should also consider input collations as a zero-length collation list.

    [ https://issues.apache.org/jira/browse/CALCITE-1498?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15685022#comment-15685022 ] 

Maryann Xue commented on CALCITE-1498:
--------------------------------------

[~julianhyde], could you please kindly review this PR for me? Thanks in advance! https://github.com/apache/calcite/pull/327

> RelMdUtil.checkInputForCollationAndLimit() should also consider input collations as a zero-length collation list.
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-1498
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1498
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.10.0
>            Reporter: Maryann Xue
>            Assignee: Maryann Xue
>            Priority: Minor
>
> {code}
>     // Check if the input is already sorted
>     boolean alreadySorted = false;
>     if (!alreadySorted) {
>       for (RelCollation inputCollation : mq.collations(input)) {
>         if (inputCollation.satisfies(collation)) {
>           alreadySorted = true;
>           break;
>         }
>       }
>     }
> {code}
> if {{mq.collations(input)}} returns an empty array, {{alreadySorted}} will always be false even if the required {{collation}} is an empty collation (which indicates there's no need to sort).



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