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https://issues.apache.org/jira/browse/CALCITE-6317?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17827758#comment-17827758
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Julian Hyde commented on CALCITE-6317:
--------------------------------------
Since the root cause is {{RelMdPredicates}}, can you add a test to
{{RelMetadataTest}}. It should be similar to {{testGetPredicatesForLiteralAgg}}.
> Incorrect constant replacement when group keys are NULL
> -------------------------------------------------------
>
> Key: CALCITE-6317
> URL: https://issues.apache.org/jira/browse/CALCITE-6317
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.36.0
> Reporter: Mihai Budiu
> Assignee: Mihai Budiu
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.37.0
>
>
> Here is a query taken from agg.iq:
> {code:sql}
> select deptno, gender, grouping_id(deptno, gender, deptno), count(*) as c
> from emp
> where deptno = 10
> group by rollup(gender, deptno)
> {code}
> The query plan initially is
> {code}
> LogicalProject(DEPTNO=[$1], GENDER=[$0], EXPR$2=[$2], C=[$3]), id = 72
> LogicalAggregate(group=[{0, 1}], groups=[[{0, 1}, {0}, {}]],
> EXPR$2=[GROUPING_ID($1, $0, $1)], C=[COUNT()]), id = 71
> LogicalProject(GENDER=[$2], DEPTNO=[$1]), id = 70
> LogicalFilter(condition=[=($1, 10)]), id = 66
> LogicalTableScan(table=[[schema, EMP]]), id = 65
> {code}
> After applying PROJECT_REDUCE_EXPRESSIONS the plan looks like:
> {code}
> LogicalProject(DEPTNO=[CAST(10):INTEGER], GENDER=[$0], EXPR$2=[$2],
> C=[$3]), id = 82
> LogicalAggregate(group=[{0, 1}], groups=[[{0, 1}, {0}, {}]],
> EXPR$2=[GROUPING_ID($1, $0, $1)], C=[COUNT()]), id = 78
> LogicalProject(GENDER=[$2], DEPTNO=[CAST(10):INTEGER]), id = 84
> LogicalFilter(condition=[=($1, 10)]), id = 74
> LogicalTableScan(table=[[schema, EMP]]), id = 65
> {code}
> The problem is in the outer LogicalProject, where the value 10 has replaced
> DEPTNO.
> However, DEPTNO can also be NULL, because of the groups in the
> LogicalAggregate.
> The constant should not be pushed past the aggregation.
>
>
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