diff options
Diffstat (limited to 'src/backend/executor/nodeLimit.c')
| -rw-r--r-- | src/backend/executor/nodeLimit.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/src/backend/executor/nodeLimit.c b/src/backend/executor/nodeLimit.c index 5ed8664f66f..c939752f37a 100644 --- a/src/backend/executor/nodeLimit.c +++ b/src/backend/executor/nodeLimit.c @@ -23,6 +23,7 @@ #include "executor/executor.h" #include "executor/nodeLimit.h" +#include "nodes/nodeFuncs.h" static void recompute_limits(LimitState *node); static void pass_down_bound(LimitState *node, PlanState *child_node); @@ -344,7 +345,19 @@ pass_down_bound(LimitState *node, PlanState *child_node) } else if (IsA(child_node, ResultState)) { - if (outerPlanState(child_node)) + /* + * An extra consideration here is that if the Result is projecting + * a targetlist that contains any SRFs, we can't assume that every + * input tuple generates an output tuple, so a Sort underneath + * might need to return more than N tuples to satisfy LIMIT N. + * So we cannot use bounded sort. + * + * If Result supported qual checking, we'd have to punt on seeing + * a qual, too. Note that having a resconstantqual is not a + * showstopper: if that fails we're not getting any rows at all. + */ + if (outerPlanState(child_node) && + !expression_returns_set((Node *) child_node->plan->targetlist)) pass_down_bound(node, outerPlanState(child_node)); } } |