[CALCITE-3404] In AggregateExpandDistinctAggregatesRule, treat all the agg expressions as distinct if they have the same arguments and the non-distinct expressions distinct constraints can be ignored

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.21.0
• Fix Version/s: 1.22.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Danny Chen
• Reporter: Danny Chen
• Created: 12/Oct/19 03:49
• Updated: 06/Mar/20 04:35
• Resolved: 14/Oct/19 02:04

Description

After CALCITE-3159, the distinct constraint for MAX/MIN/BIT_OR/BIT_AND are removed automatically, so if we have a query:

select sum(distinct deptno), count(distinct deptno), max(deptno) from emp

The plan has regression from

LogicalAggregate(group=[{}], EXPR$0=[SUM($0)], EXPR$1=[COUNT($0)], EXPR$2=[MAX($0)])
  LogicalAggregate(group=[{0}])
    LogicalProject(DEPTNO=[$7])
      LogicalTableScan(table=[[CATALOG, SALES, EMP]])

to

LogicalAggregate(group=[{}], EXPR$0=[SUM($0) FILTER $2], EXPR$1=[COUNT($0) FILTER $2], EXPR$2=[MIN($1) FILTER $3])
  LogicalProject(DEPTNO=[$0], EXPR$2=[$1], $g_0=[=($2, 0)], $g_1=[=($2, 1)])
    LogicalAggregate(group=[{0}], groups=[[{0}, {}]], EXPR$2=[MAX($0)], $g=[GROUPING($0)])
      LogicalProject(DEPTNO=[$7])
        LogicalTableScan(table=[[CATALOG, SALES, EMP]])

The distinct trait actually can be reused.

Issue Links

• links to: GitHub Pull Request #1498