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Julian Hyde commented on CALCITE-1288: -------------------------------------- Did you consider leveraging CALCITE-732? > Avoid doing the same join twice if count(distinct) exists > --------------------------------------------------------- > > Key: CALCITE-1288 > URL: https://issues.apache.org/jira/browse/CALCITE-1288 > Project: Calcite > Issue Type: Improvement > Reporter: Gautam Kumar Parai > Assignee: Gautam Kumar Parai > > When the query has one distinct aggregate and one or more non-distinct > aggregates, the join instance need not produce the join-based plan. We can > generate multi-phase aggregates. > {code} > select emp.empno, count(*), avg(distinct dept.deptno) > from sales.emp emp inner join sales.dept dept > on emp.deptno = dept.deptno > group by emp.empno > LogicalProject(EMPNO=[$0], EXPR$1=[$1], EXPR$2=[$3]) > LogicalJoin(condition=[IS NOT DISTINCT FROM($0, $2)], joinType=[inner]) > LogicalAggregate(group=[{0}], EXPR$1=[COUNT()]) > LogicalProject(EMPNO=[$0], DEPTNO0=[$9]) > LogicalJoin(condition=[=($7, $9)], joinType=[inner]) > LogicalTableScan(table=[[CATALOG, SALES, EMP]]) > LogicalTableScan(table=[[CATALOG, SALES, DEPT]]) > LogicalAggregate(group=[{0}], EXPR$2=[AVG($1)]) > LogicalAggregate(group=[{0, 1}]) > LogicalProject(EMPNO=[$0], DEPTNO0=[$9]) > LogicalJoin(condition=[=($7, $9)], joinType=[inner]) > LogicalTableScan(table=[[CATALOG, SALES, EMP]]) > LogicalTableScan(table=[[CATALOG, SALES, DEPT]]) > {code} > The more efficient form should look like > {code} > select emp.empno, count(*), avg(distinct dept.deptno) > from sales.emp emp inner join sales.dept dept > on emp.deptno = dept.deptno > group by emp.empno > LogicalAggregate(group=[{0}], EXPR$1=[SUM($2)], EXPR$2=[AVG($1)]) > LogicalAggregate(group=[{0, 1}], EXPR$1=[COUNT()]) > LogicalProject(EMPNO=[$0], DEPTNO0=[$9]) > LogicalJoin(condition=[=($7, $9)], joinType=[inner]) > LogicalTableScan(table=[[CATALOG, SALES, EMP]]) > LogicalTableScan(table=[[CATALOG, SALES, DEPT]]) > {code} -- This message was sent by Atlassian JIRA (v6.3.4#6332)