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https://issues.apache.org/jira/browse/CALCITE-4634?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Yingyu updated CALCITE-4634:
----------------------------
Description:
*AggregateProjectPullUpConstantsRule* removes constant keys from an Aggregate.
However, this rules never removes the last column, because Aggregate([])
returns 1 row even if its input is empty.
The problem is if the remaining last column is a constant, it will fail on *SQL
Server* with this error:
"Each GROUP BY expression must contain at least one column that is not an
outer reference."
To improve on this we can improve the AggregateProjectPullUpConstantsRule to:
- Remove all constant keys from an Aggregate
- When no GROUP BY column is left, add a filter to the Aggregate([]) so that
it returns empty dataset if its input is empty.
E.g.
select 'abc' from table_name group by ('abc')
will be translated to:
select 'abc' from table_name group by () having count(*) > 0
was:
AggregateProjectPullUpConstantsRule removes constant keys from an Aggregate.
However, this rules never removes the last column, because Aggregate([])
returns 1 row even if its input is empty.
The problem is if the remaining last column is a constant, it will fail on SQL
Server with this error:
"Each GROUP BY expression must contain at least one column that is not an outer
reference."
To improve on this we can improve the AggregateProjectPullUpConstantsRule to:
- Remove all constant keys from an Aggregate
- When no GROUP BY column is left, add a filter to the Aggregate([]) so that it
returns empty dataset if its input is empty.
E.g.
select 'abc' from table_name group by ('abc')
will be translated to:
select 'abc' from table_name group by () having count(*) > 0
> Improve AggregateProjectPullUpConstantsRule to remove all constant keys
> -----------------------------------------------------------------------
>
> Key: CALCITE-4634
> URL: https://issues.apache.org/jira/browse/CALCITE-4634
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.16.0
> Reporter: Yingyu
> Priority: Major
>
> *AggregateProjectPullUpConstantsRule* removes constant keys from an
> Aggregate. However, this rules never removes the last column, because
> Aggregate([]) returns 1 row even if its input is empty.
> The problem is if the remaining last column is a constant, it will fail on
> *SQL Server* with this error:
> "Each GROUP BY expression must contain at least one column that is not an
> outer reference."
>
> To improve on this we can improve the AggregateProjectPullUpConstantsRule to:
> - Remove all constant keys from an Aggregate
> - When no GROUP BY column is left, add a filter to the Aggregate([]) so that
> it returns empty dataset if its input is empty.
>
> E.g.
> select 'abc' from table_name group by ('abc')
> will be translated to:
> select 'abc' from table_name group by () having count(*) > 0
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