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https://issues.apache.org/jira/browse/CALCITE-7116?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zhen Chen updated CALCITE-7116:
-------------------------------
Description:
Currently, GROUPING SETS operations may not be optimally executed in some
cases. This ticket proposes a rule to transform GROUPING SETS into a series of
UNION ALL operations, each with its own GROUP BY clause.
Original query:
{code:java}
SELECT a, b, c FROM t GROUP BY GROUPING SETS ((a,b), (a,c))
{code}
Transformed to:
{code:java}
SELECT a, b, NULL AS c FROM t GROUP BY a, b
UNION ALL
SELECT a, NULL AS b, c FROM t GROUP BY a, c
{code}
was:
Currently, GROUPING SETS operations may not be optimally executed in some
cases. This ticket proposes a rule to transform GROUPING SETS into a series of
UNION ALL operations, each with its own GROUP BY clause.
{code:java}
SELECT a, b, c FROM t GROUP BY GROUPING SETS ((a,b), (a,c))
{code}
{code:java}
SELECT a, b, NULL AS c FROM t GROUP BY a, b
UNION ALL
SELECT a, NULL AS b, c FROM t GROUP BY a, c
{code}
> Optimize queries with GROUPING SETS by converting them into equivalent UNION
> ALL of GROUP BY operations.
> --------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-7116
> URL: https://issues.apache.org/jira/browse/CALCITE-7116
> Project: Calcite
> Issue Type: New Feature
> Components: core
> Reporter: Zhen Chen
> Priority: Minor
> Fix For: 1.41.0
>
>
> Currently, GROUPING SETS operations may not be optimally executed in some
> cases. This ticket proposes a rule to transform GROUPING SETS into a series
> of UNION ALL operations, each with its own GROUP BY clause.
> Original query:
> {code:java}
> SELECT a, b, c FROM t GROUP BY GROUPING SETS ((a,b), (a,c))
> {code}
> Transformed to:
> {code:java}
> SELECT a, b, NULL AS c FROM t GROUP BY a, b
> UNION ALL
> SELECT a, NULL AS b, c FROM t GROUP BY a, c
> {code}
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