diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 9d912a84457..e165810e807 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -2088,22 +2088,14 @@ fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
if (IsA(node, Aggref))
{
Aggref *aggref = (Aggref *) node;
+ Param *aggparam;
/* See if the Aggref should be replaced by a Param */
- if (context->root->minmax_aggs != NIL &&
- list_length(aggref->args) == 1)
+ aggparam = find_minmax_agg_replacement_param(context->root, aggref);
+ if (aggparam != NULL)
{
- TargetEntry *curTarget = (TargetEntry *) linitial(aggref->args);
- ListCell *lc;
-
- foreach(lc, context->root->minmax_aggs)
- {
- MinMaxAggInfo *mminfo = (MinMaxAggInfo *) lfirst(lc);
-
- if (mminfo->aggfnoid == aggref->aggfnoid &&
- equal(mminfo->target, curTarget->expr))
- return (Node *) copyObject(mminfo->param);
- }
+ /* Make a copy of the Param for paranoia's sake */
+ return (Node *) copyObject(aggparam);
}
/* If no match, just fall through to process it normally */
}
@@ -3030,22 +3022,14 @@ fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context)
if (IsA(node, Aggref))
{
Aggref *aggref = (Aggref *) node;
+ Param *aggparam;
/* See if the Aggref should be replaced by a Param */
- if (context->root->minmax_aggs != NIL &&
- list_length(aggref->args) == 1)
+ aggparam = find_minmax_agg_replacement_param(context->root, aggref);
+ if (aggparam != NULL)
{
- TargetEntry *curTarget = (TargetEntry *) linitial(aggref->args);
- ListCell *lc;
-
- foreach(lc, context->root->minmax_aggs)
- {
- MinMaxAggInfo *mminfo = (MinMaxAggInfo *) lfirst(lc);
-
- if (mminfo->aggfnoid == aggref->aggfnoid &&
- equal(mminfo->target, curTarget->expr))
- return (Node *) copyObject(mminfo->param);
- }
+ /* Make a copy of the Param for paranoia's sake */
+ return (Node *) copyObject(aggparam);
}
/* If no match, just fall through to process it normally */
}
@@ -3199,6 +3183,38 @@ set_windowagg_runcondition_references(PlannerInfo *root,
return newlist;
}
+/*
+ * find_minmax_agg_replacement_param
+ * If the given Aggref is one that we are optimizing into a subquery
+ * (cf. planagg.c), then return the Param that should replace it.
+ * Else return NULL.
+ *
+ * This is exported so that SS_finalize_plan can use it before setrefs.c runs.
+ * Note that it will not find anything until we have built a Plan from a
+ * MinMaxAggPath, as root->minmax_aggs will never be filled otherwise.
+ */
+Param *
+find_minmax_agg_replacement_param(PlannerInfo *root, Aggref *aggref)
+{
+ if (root->minmax_aggs != NIL &&
+ list_length(aggref->args) == 1)
+ {
+ TargetEntry *curTarget = (TargetEntry *) linitial(aggref->args);
+ ListCell *lc;
+
+ foreach(lc, root->minmax_aggs)
+ {
+ MinMaxAggInfo *mminfo = (MinMaxAggInfo *) lfirst(lc);
+
+ if (mminfo->aggfnoid == aggref->aggfnoid &&
+ equal(mminfo->target, curTarget->expr))
+ return mminfo->param;
+ }
+ }
+ return NULL;
+}
+
+
/*****************************************************************************
* QUERY DEPENDENCY MANAGEMENT
*****************************************************************************/
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index a1957883baf..61b12384313 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -2849,8 +2849,8 @@ finalize_plan(PlannerInfo *root, Plan *plan,
}
/*
- * finalize_primnode: add IDs of all PARAM_EXEC params appearing in the given
- * expression tree to the result set.
+ * finalize_primnode: add IDs of all PARAM_EXEC params that appear (or will
+ * appear) in the given expression tree to the result set.
*/
static bool
finalize_primnode(Node *node, finalize_primnode_context *context)
@@ -2867,7 +2867,26 @@ finalize_primnode(Node *node, finalize_primnode_context *context)
}
return false; /* no more to do here */
}
- if (IsA(node, SubPlan))
+ else if (IsA(node, Aggref))
+ {
+ /*
+ * Check to see if the aggregate will be replaced by a Param
+ * referencing a subquery output during setrefs.c. If so, we must
+ * account for that Param here. (For various reasons, it's not
+ * convenient to perform that substitution earlier than setrefs.c, nor
+ * to perform this processing after setrefs.c. Thus we need a wart
+ * here.)
+ */
+ Aggref *aggref = (Aggref *) node;
+ Param *aggparam;
+
+ aggparam = find_minmax_agg_replacement_param(context->root, aggref);
+ if (aggparam != NULL)
+ context->paramids = bms_add_member(context->paramids,
+ aggparam->paramid);
+ /* Fall through to examine the agg's arguments */
+ }
+ else if (IsA(node, SubPlan))
{
SubPlan *subplan = (SubPlan *) node;
Plan *plan = planner_subplan_get_plan(context->root, subplan);
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index c4f61c1a09c..6f87ee3258d 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -113,6 +113,8 @@ extern bool innerrel_is_unique(PlannerInfo *root,
*/
extern Plan *set_plan_references(PlannerInfo *root, Plan *plan);
extern bool trivial_subqueryscan(SubqueryScan *plan);
+extern Param *find_minmax_agg_replacement_param(PlannerInfo *root,
+ Aggref *aggref);
extern void record_plan_function_dependency(PlannerInfo *root, Oid funcid);
extern void record_plan_type_dependency(PlannerInfo *root, Oid typid);
extern bool extract_query_dependencies_walker(Node *node, PlannerInfo *root);
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index 26031bc7800..6b3b9f103d8 100644
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -1249,6 +1249,37 @@ NOTICE: drop cascades to 3 other objects
DETAIL: drop cascades to table minmaxtest1
drop cascades to table minmaxtest2
drop cascades to table minmaxtest3
+-- DISTINCT can also trigger wrong answers with hash aggregation (bug #18465)
+begin;
+set local enable_sort = off;
+explain (costs off)
+ select f1, (select distinct min(t1.f1) from int4_tbl t1 where t1.f1 = t0.f1)
+ from int4_tbl t0;
+ QUERY PLAN
+---------------------------------------------------------------------
+ Seq Scan on int4_tbl t0
+ SubPlan 2
+ -> HashAggregate
+ Group Key: $1
+ InitPlan 1 (returns $1)
+ -> Limit
+ -> Seq Scan on int4_tbl t1
+ Filter: ((f1 IS NOT NULL) AND (f1 = t0.f1))
+ -> Result
+(9 rows)
+
+select f1, (select distinct min(t1.f1) from int4_tbl t1 where t1.f1 = t0.f1)
+from int4_tbl t0;
+ f1 | min
+-------------+-------------
+ 0 | 0
+ 123456 | 123456
+ -123456 | -123456
+ 2147483647 | 2147483647
+ -2147483647 | -2147483647
+(5 rows)
+
+rollback;
-- check for correct detection of nested-aggregate errors
select max(min(unique1)) from tenk1;
ERROR: aggregate function calls cannot be nested
diff --git a/src/test/regress/sql/aggregates.sql b/src/test/regress/sql/aggregates.sql
index 48bea8af5f8..b89cf26c5a2 100644
--- a/src/test/regress/sql/aggregates.sql
+++ b/src/test/regress/sql/aggregates.sql
@@ -431,6 +431,16 @@ select distinct min(f1), max(f1) from minmaxtest;
drop table minmaxtest cascade;
+-- DISTINCT can also trigger wrong answers with hash aggregation (bug #18465)
+begin;
+set local enable_sort = off;
+explain (costs off)
+ select f1, (select distinct min(t1.f1) from int4_tbl t1 where t1.f1 = t0.f1)
+ from int4_tbl t0;
+select f1, (select distinct min(t1.f1) from int4_tbl t1 where t1.f1 = t0.f1)
+from int4_tbl t0;
+rollback;
+
-- check for correct detection of nested-aggregate errors
select max(min(unique1)) from tenk1;
select (select max(min(unique1)) from int8_tbl) from tenk1;