[CALCITE-896] Remove Aggregate if grouping columns are unique and all functions are splittable

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.20.0
• Labels: pull-request-available
• Assignee: Haisheng Yuan
• Reporter: Julian Hyde
• Created: 22/Sep/15 00:14
• Updated: 24/Jun/19 15:01
• Resolved: 12/Apr/19 21:40

Description

Remove Aggregate if grouping columns are unique and all functions are splittable. Currently AggregateRemoveRule is only applied if there are no aggregate functions. But we could optimize

select deptno, count(name) from dept group by deptno

to

select deptno, 1 from dept

because we know deptno is unique, name is not null, and a singleton count applied to a not null column evaluates to 1.

See AggregateJoinTransposeRule; it already makes use of SqlSplittableAggFunction.

Issue Links

• is related to: CALCITE-751 Push aggregate with aggregate functions through join
• links to: GitHub Pull Request #1078