[
https://issues.apache.org/jira/browse/FLINK-7144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16394377#comment-16394377
]
Rong Rong commented on FLINK-7144:
----------------------------------
Hi [~jark], I am working on FLINK-8688 and I think I can use the fix for this
JIRA first before I consolidate all DISTINCT AGG,
if you haven't started, can I try implementing the optimization for this JIRA
together?
> Optimize multiple LogicalAggregate into one
> -------------------------------------------
>
> Key: FLINK-7144
> URL: https://issues.apache.org/jira/browse/FLINK-7144
> Project: Flink
> Issue Type: Improvement
> Components: Table API & SQL
> Reporter: Jark Wu
> Priority: Major
>
> When applying multiple GROUP BY, and no aggregates or expression in the first
> GROUP BY, and the second GROUP fields is a subset of first GROUP fields.
> Then the first GROUP BY can be removed.
> Such as the following SQL ,
> {code}
> SELECT a FROM (SELECT a,b,c FROM MyTable GROUP BY a, b, c) GROUP BY a
> {code}
> should be optimized into
> {code}
> DataStreamGroupAggregate(groupBy=[a], select=[a])
> DataStreamCalc(select=[a])
> DataStreamScan(table=[[_DataStreamTable_0]])
> {code}
> but get:
> {code}
> DataStreamGroupAggregate(groupBy=[a], select=[a])
> DataStreamCalc(select=[a])
> DataStreamGroupAggregate(groupBy=[a, b, c], select=[a, b, c])
> DataStreamScan(table=[[_DataStreamTable_0]])
> {code}
> I looked for the Calcite built-in rules, but can't find a match one. So maybe
> we should implement one , and maybe we should implement it in Calcite.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
