[jira] [Resolved] (CALCITE-3893) SQL with GROUP_ID may generate wrong plan

["Feng Zhu (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-3893?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Feng Zhu resolved CALCITE-3893.
-------------------------------
    Resolution: Not A Problem

> SQL with GROUP_ID may generate wrong plan
> -----------------------------------------
>
>                 Key: CALCITE-3893
>                 URL: https://issues.apache.org/jira/browse/CALCITE-3893
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.22.0
>            Reporter: Shuo Cheng
>            Assignee: Feng Zhu
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.23.0
>
>          Time Spent: 2h
>  Remaining Estimate: 0h
>
> Consider the following SQL:
> {code:java}
> select 
>   deptno, group_id() as g, count(*) as c
> from emp 
> group by grouping sets (deptno, (), ())
> {code}
> the plan after SqlToRel is:
> {code:java}
> LogicalUnion(all=[true])
>   LogicalProject(DEPTNO=[$0], G=[0:BIGINT], C=[$1])
>     LogicalAggregate(group=[{0}], groups=[[{0}, {}]], C=[COUNT()])
>       LogicalProject(DEPTNO=[$7])
>         LogicalTableScan(table=[[CATALOG, SALES, EMP]])
>   LogicalProject(DEPTNO=[$0], G=[1:BIGINT], C=[$1])
>     LogicalAggregate(group=[{0}], groups=[[{}]], C=[COUNT()])
>       LogicalProject(DEPTNO=[$7])
>         LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> I'm afraid there's some semantic problems here. As `groups` of the second Aggregate is empty, then what is `$0` meaning in the Project above it. Maybe that we want is:
> {code:java}
> LogicalUnion(all=[true])
>   LogicalProject(DEPTNO=[$0], G=[0:BIGINT], C=[$1])
>     LogicalAggregate(group=[{0}], groups=[[{0}, {}]], C=[COUNT()])
>       LogicalProject(DEPTNO=[$7])
>         LogicalTableScan(table=[[CATALOG, SALES, EMP]])
>   LogicalProject(DEPTNO=[$0], G=[1:BIGINT], C=[$1])
>     LogicalAggregate(group=[{0}], groups=[[{0}]], C=[COUNT()])
>       LogicalProject(DEPTNO=[null])
>         LogicalTableScan(table=[[CATALOG, SALES, EMP]]){code}
> I noticed this is introduced by CALCITE-1824, cc [~donnyzone], [~vladimirsitnikov].



--
This message was sent by Atlassian Jira
(v8.3.4#803005)