[jira] [Commented] (CALCITE-4182) MV recognition fails when query has constant filter for group by list in mv, but without group by

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

    [ https://issues.apache.org/jira/browse/CALCITE-4182?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17206360#comment-17206360 ] 

Julian Hyde commented on CALCITE-4182:
--------------------------------------

[~rubenql], Please see my comments above about commit the message, and improve the commit message when you write the release notes.

> MV recognition fails when query has constant filter for group by list in mv, but without group by
> -------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-4182
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4182
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Wang Yanlin
>            Assignee: Wang Yanlin
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.26.0
>
>          Time Spent: 1h 10m
>  Remaining Estimate: 0h
>
> MV recognition fails when query has constant filter for group by list in mv, but has no group by itself.
> {noformat}
> @Test void testConstantFilterInAgg() {
>     final String mv = ""
>         + "select \"name\", count(distinct \"deptno\") as cnt\n"
>         + "from \"emps\" group by \"name\"";
>     final String query = ""
>         + "select count(distinct \"deptno\") as cnt\n"
>         + "from \"emps\" where \"name\" = 'hello'";
>     sql(mv, query).ok();
>   }
> {noformat}
> This case fails, however we can see that, we can rewrite the query with mv like this, suppose *mv* is the name of the table.
> {noformat}
> select cnt from mv where name = 'hello';
> {noformat}
> However, this query has the same semantics with the query in the case, using this query for mv recognition, the case will success
> {noformat}
> final String query = ""
>         + "select cnt from(\n"
>         + " select \"name\", count(distinct \"deptno\") as cnt "
>         + " from \"emps\" group by \"name\") t\n"
>         + "where \"name\" = 'hello'";
> {noformat}
> But we cannot force users to only write their queries in this way, so maybe we need to enhance  the mv recognition ability of {{AggregateOnCalcToAggregateUnifyRule to cover this case.}}



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