diff options
Diffstat (limited to 'src/backend/optimizer')
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 20 |
1 files changed, 9 insertions, 11 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index b31c52404a4..e664eb18c05 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -3056,14 +3056,16 @@ limit_needed(Query *parse) * Since some other DBMSes do not allow references to ungrouped columns, it's * not unusual to find all columns listed in GROUP BY even though listing the * primary-key columns would be sufficient. Deleting such excess columns - * avoids redundant sorting work, so it's worth doing. When we do this, we - * must mark the plan as dependent on the pkey constraint (compare the - * parser's check_ungrouped_columns() and check_functional_grouping()). + * avoids redundant sorting work, so it's worth doing. * - * In principle, we could treat any NOT-NULL columns appearing in a UNIQUE - * index as the determining columns. But as with check_functional_grouping(), - * there's currently no way to represent dependency on a NOT NULL constraint, - * so we consider only the pkey for now. + * Relcache invalidations will ensure that cached plans become invalidated + * when the underlying index of the pkey constraint is dropped. + * + * Currently, we only make use of pkey constraints for this, however, we may + * wish to take this further in the future and also use unique constraints + * which have NOT NULL columns. In that case, plan invalidation will still + * work since relations will receive a relcache invalidation when a NOT NULL + * constraint is dropped. */ static void remove_useless_groupby_columns(PlannerInfo *root) @@ -3172,10 +3174,6 @@ remove_useless_groupby_columns(PlannerInfo *root) /* Remember the attnos of the removable columns */ surplusvars[relid] = bms_difference(relattnos, pkattnos); - - /* Also, mark the resulting plan as dependent on this constraint */ - parse->constraintDeps = lappend_oid(parse->constraintDeps, - constraintOid); } } |