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https://issues.apache.org/jira/browse/CALCITE-5000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17490753#comment-17490753
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Xurenhe commented on CALCITE-5000:
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As [~nobigo] suggested, I add some common functions, which could be simplified
by grouping.
{code:java}
-- group by x
sum(x) => x
count(x) => case when x is not null then 1 else 0
avg(x) => x
max(x) => x
min(x) => x
sum0(x) => coalesce(x, 0)
any_value(x) => x {code}
> Expand rule of `AGGREGATE_REDUCE_FUNCTIONS`Expand
> `AGGREGATE_REDUCE_FUNCTIONS`, when arg of agg-call is in the aggregate's group
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-5000
> URL: https://issues.apache.org/jira/browse/CALCITE-5000
> Project: Calcite
> Issue Type: Improvement
> Reporter: Xurenhe
> Assignee: Xurenhe
> Priority: Major
> Labels: pull-request-available
> Time Spent: 1h
> Remaining Estimate: 0h
>
> Using calcite's SubstitutionVisitor, we need do a lot work about
> canonicalizing relnode.
> Some sql should be simplified.
> {noformat}
> -- origin sql
> select deptno, salary, max(salary), min(commission)
> from emps
> group by deptno, salary
> -- simplified
> select deptno, salary, salary as expr, min(commission)
> from emps
> group by deptno, salary{noformat}
> It should be simplified, but I didn't find any rule to simplify it.
> This issue is related to CALCITE-4857
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