You are viewing a plain text version of this content. The canonical link for it is here.

Posted to issues@calcite.apache.org by "Jacques Nadeau (JIRA)" <ji...@apache.org> on 2015/09/01 05:02:50 UTC

[jira] [Closed] (CALCITE-732) Implement multiple distinct-COUNT using GROUPING SETS

     [ https://issues.apache.org/jira/browse/CALCITE-732?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jacques Nadeau closed CALCITE-732.
----------------------------------

Resolved in release 1.4.0-incubating (2015-08-23)

> Implement multiple distinct-COUNT using GROUPING SETS
> -----------------------------------------------------
>
>                 Key: CALCITE-732
>                 URL: https://issues.apache.org/jira/browse/CALCITE-732
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Assignee: Julian Hyde
>             Fix For: 1.4.0-incubating
>
>
> Currently if a query has COUNT(DISTINCT x) and COUNT(DISTINCT y) we compute the distinct counts separately and combine them using a join. The join isn't too expensive (because usually the GROUP BY has only a few keys) but we make multiple scans over the base table.
> I think we could translate multiple distinct-counts into a GROUPING SETS query (i.e. an Aggregate with more than one element in the groupSets field). If the underlying engine can evaluate that efficiently, then we have saved ourselves a join and several scans.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)