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Posted to issues@calcite.apache.org by "Steven Talbot (Jira)" <ji...@apache.org> on 2020/04/24 21:16:00 UTC
[jira] [Commented] (CALCITE-3957) AggregateMergeRule should be able
to merge SUM0 into COUNT even with empty group by
[ https://issues.apache.org/jira/browse/CALCITE-3957?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17091906#comment-17091906 ]
Steven Talbot commented on CALCITE-3957:
----------------------------------------
See some discussion where this was originally implemented on CALCITE-1172
> AggregateMergeRule should be able to merge SUM0 into COUNT even with empty group by
> -----------------------------------------------------------------------------------
>
> Key: CALCITE-3957
> URL: https://issues.apache.org/jira/browse/CALCITE-3957
> Project: Calcite
> Issue Type: Bug
> Reporter: Steven Talbot
> Priority: Major
>
> Basically, the comment at [https://github.com/apache/calcite/blame/571731b80a58eb095ebac7123285c375e7afff90/core/src/main/java/org/apache/calcite/rel/rules/AggregateMergeRule.java#L117-L120] does not apply if the top aggregate is a SUM0, I believe. Without a fix for this, there's this one case where this rule falls down and isn't able to merge something that just got rolled up: otherwise it's a pretty nice invariant that if one of our standard rollup rules for aggregates (say, in MaterializedViewRule) just split the aggregate, this rule should be able to merge it back.
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