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https://issues.apache.org/jira/browse/CALCITE-4665?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17373111#comment-17373111
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Julian Hyde commented on CALCITE-4665:
--------------------------------------
That makes sense. When you say there's a bug, do you mean a bug in Calcite? If
so, what is the bug?
I want to point out that Hive SQL's GROUPING SETS behavior is very
non-standard. It is able set bits in {{Aggregate.group}} that are not present
in any of the {{Aggregate.groups}} bitmaps.
Should Calcite SQL attempt to be compatible with Hive SQL? Absolutely not.
Should we allow {{RelBuilder}} to create things like this:
{noformat}
Aggregate(group=[{0, 1, 2}], groups=[[{0, 1}]], C=[COUNT()],
S=[SUM($5)]){noformat}
Maybe we should. They cannot arise directly from standard SQL but they might
occur if a {{Filter}} is pushed into an {{Aggregate}}. (The "2" represents the
"JOB" column, and its value in this query will always be NULL.)
So, let's figure out an answer to that question.
> When group by are same as sub-query, grouping sets are missing
> --------------------------------------------------------------
>
> Key: CALCITE-4665
> URL: https://issues.apache.org/jira/browse/CALCITE-4665
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.22.0
> Reporter: xiejiajun
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.28.0
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> UT:
> {code:java}
> builder.scan("EMP")
> .aggregate(builder.groupKey(0, 1, 7),
> builder.aggregateCall(SqlStdOperatorTable.COUNT,
> builder.field("JOB")).as("job_num"))
> .aggregate(
> builder.groupKey(ImmutableBitSet.of(0, 1, 2),
> (Iterable<ImmutableBitSet>)
> ImmutableList.of(ImmutableBitSet.of(0, 1))))
> // GROUP BY 0,1,2 GROUPING SETS((0, 1))
> .build();
> {code}
> Before I fixed it, you can see groupings set are missing because
> LogicalProject.
> {code:java}
> LogicalProject(EMPNO=[$0], ENAME=[$1], DEPTNO=[$2])
> LogicalAggregate(group=[{0, 1, 7}], job_num=[COUNT($2)])
> LogicalTableScan(table=[[scott, EMP]]){code}
> After I fixed it, groupings set will be saved.
> {code:java}
> LogicalAggregate(group=[{0, 1, 2}], groups=[[{0, 1}]])
> LogicalAggregate(group=[{0, 1, 7}], job_num=[COUNT($2)])
> LogicalTableScan(table=[[scott, EMP]]{code}
> Although the user will not write such SQL directly, it does happen after
> the logic is complicated, and the user will be confused about the wrong data.
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