diff options
Diffstat (limited to 'src/backend/optimizer/plan/planner.c')
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index a3cc27464c1..4f8e4c07d61 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -653,13 +653,19 @@ subquery_planner(PlannerGlobal *glob, Query *parse, * In some cases we may want to transfer a HAVING clause into WHERE. We * cannot do so if the HAVING clause contains aggregates (obviously) or * volatile functions (since a HAVING clause is supposed to be executed - * only once per group). Also, it may be that the clause is so expensive - * to execute that we're better off doing it only once per group, despite - * the loss of selectivity. This is hard to estimate short of doing the - * entire planning process twice, so we use a heuristic: clauses - * containing subplans are left in HAVING. Otherwise, we move or copy the - * HAVING clause into WHERE, in hopes of eliminating tuples before - * aggregation instead of after. + * only once per group). We also can't do this if there are any nonempty + * grouping sets; moving such a clause into WHERE would potentially change + * the results, if any referenced column isn't present in all the grouping + * sets. (If there are only empty grouping sets, then the HAVING clause + * must be degenerate as discussed below.) + * + * Also, it may be that the clause is so expensive to execute that we're + * better off doing it only once per group, despite the loss of + * selectivity. This is hard to estimate short of doing the entire + * planning process twice, so we use a heuristic: clauses containing + * subplans are left in HAVING. Otherwise, we move or copy the HAVING + * clause into WHERE, in hopes of eliminating tuples before aggregation + * instead of after. * * If the query has explicit grouping then we can simply move such a * clause into WHERE; any group that fails the clause will not be in the @@ -679,7 +685,8 @@ subquery_planner(PlannerGlobal *glob, Query *parse, { Node *havingclause = (Node *) lfirst(l); - if (contain_agg_clause(havingclause) || + if ((parse->groupClause && parse->groupingSets) || + contain_agg_clause(havingclause) || contain_volatile_functions(havingclause) || contain_subplans(havingclause)) { |