diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 8b4425dcf90ddd5762bd2881c262b059b683c2e8..fa53b7a8c5050c579fa27d79340a6d9374a8e1f5 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -1223,13 +1223,17 @@ max_parallel_hazard_walker(Node *node, max_parallel_hazard_context *context)
/*
* We can't pass Params to workers at the moment either, so they are also
- * parallel-restricted, unless they are PARAM_EXEC Params listed in
- * safe_param_ids, meaning they could be generated within the worker.
+ * parallel-restricted, unless they are PARAM_EXTERN Params or are
+ * PARAM_EXEC Params listed in safe_param_ids, meaning they could be
+ * generated within the worker.
*/
else if (IsA(node, Param))
{
Param *param = (Param *) node;
+ if (param->paramkind == PARAM_EXTERN)
+ return false;
+
if (param->paramkind != PARAM_EXEC ||
!list_member_int(context->safe_param_ids, param->paramid))
{
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index c98492b2a42484fdd7ce256cf5c2947cadb79258..d4333b6dc27ab20f84dd022a62a5c9af6917f0f5 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -6821,7 +6821,7 @@ exec_simple_recheck_plan(PLpgSQL_expr *expr, CachedPlan *cplan)
{
PlannedStmt *stmt;
Plan *plan;
- TargetEntry *tle;
+ Expr *tle_expr;
/*
* Initialize to "not simple", and remember the plan generation number we
@@ -6836,18 +6836,51 @@ exec_simple_recheck_plan(PLpgSQL_expr *expr, CachedPlan *cplan)
if (list_length(cplan->stmt_list) != 1)
return;
stmt = linitial_node(PlannedStmt, cplan->stmt_list);
+ if (stmt->commandType != CMD_SELECT)
+ return;
/*
- * 2. It must be a RESULT plan --> no scan's required
+ * 2. Ordinarily, the plan node should be a simple Result. However, if
+ * force_parallel_mode is on, the planner might've stuck a Gather node
+ * atop that. The simplest way to deal with this is to look through the
+ * Gather node. The Gather node's tlist would normally contain a Var
+ * referencing the child node's output, but it could also be a Param, or
+ * it could be a Const that setrefs.c copied as-is.
*/
- if (stmt->commandType != CMD_SELECT)
- return;
plan = stmt->planTree;
- if (!IsA(plan, Result))
- return;
+ for (;;)
+ {
+ /*
+ * 3. The plan must have a single attribute as result
+ */
+ if (list_length(plan->targetlist) != 1)
+ return;
+ tle_expr = castNode(TargetEntry, linitial(plan->targetlist))->expr;
+
+ if (IsA(plan, Gather))
+ {
+ if (plan->righttree != NULL ||
+ plan->initPlan != NULL ||
+ plan->qual != NULL)
+ return;
+ /* If setrefs.c copied up a Const, no need to look further */
+ if (IsA(tle_expr, Const))
+ break;
+ /* Otherwise, it had better be a Param or an outer Var */
+ if (!IsA(tle_expr, Param) && !(IsA(tle_expr, Var) &&
+ ((Var *) tle_expr)->varno == OUTER_VAR))
+ return;
+ /* Descend to the child node */
+ plan = plan->lefttree;
+ continue;
+ }
+ else if (!IsA(plan, Result))
+ return;
+ break;
+ }
/*
- * 3. Can't have any subplan or qual clause, either
+ * 4. Can't have any subplan or qual clause, either
*/
if (plan->lefttree != NULL ||
plan->righttree != NULL ||
@@ -6856,31 +6889,23 @@ exec_simple_recheck_plan(PLpgSQL_expr *expr, CachedPlan *cplan)
((Result *) plan)->resconstantqual != NULL)
return;
- /*
- * 4. The plan must have a single attribute as result
- */
- if (list_length(plan->targetlist) != 1)
- return;
-
- tle = (TargetEntry *) linitial(plan->targetlist);
-
/*
* 5. Check that all the nodes in the expression are non-scary.
*/
- if (!exec_simple_check_node((Node *) tle->expr))
+ if (!exec_simple_check_node((Node *) tle_expr))
return;
/*
* Yes - this is a simple expression. Mark it as such, and initialize
* state to "not valid in current transaction".
*/
- expr->expr_simple_expr = tle->expr;
+ expr->expr_simple_expr = tle_expr;
expr->expr_simple_state = NULL;
expr->expr_simple_in_use = false;
expr->expr_simple_lxid = InvalidLocalTransactionId;
/* Also stash away the expression result type */
- expr->expr_simple_type = exprType((Node *) tle->expr);
- expr->expr_simple_typmod = exprTypmod((Node *) tle->expr);
+ expr->expr_simple_type = exprType((Node *) tle_expr);
+ expr->expr_simple_typmod = exprTypmod((Node *) tle_expr);
}
/*
diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out
index 6bbcd34b800e0cc76f14f028bdd0de0eafe4ccd8..f3e8b565871b62f852160df1be772dd89709f66f 100644
--- a/src/test/regress/expected/select_parallel.out
+++ b/src/test/regress/expected/select_parallel.out
@@ -101,6 +101,26 @@ explain (costs off)
-> Parallel Index Only Scan using tenk1_unique1 on tenk1
(5 rows)
+-- test prepared statement
+prepare tenk1_count(integer) As select count((unique1)) from tenk1 where hundred > $1;
+explain (costs off) execute tenk1_count(1);
+ QUERY PLAN
+----------------------------------------------
+ Finalize Aggregate
+ -> Gather
+ Workers Planned: 4
+ -> Partial Aggregate
+ -> Parallel Seq Scan on tenk1
+ Filter: (hundred > 1)
+(6 rows)
+
+execute tenk1_count(1);
+ count
+-------
+ 9800
+(1 row)
+
+deallocate tenk1_count;
-- test parallel plans for queries containing un-correlated subplans.
alter table tenk2 set (parallel_workers = 0);
explain (costs off)
diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql
index cf02d84c8d8fa198f69be53ef09710b3619a690c..d2eee147e99e55d8c36e37e79de78dcbb8ef677a 100644
--- a/src/test/regress/sql/select_parallel.sql
+++ b/src/test/regress/sql/select_parallel.sql
@@ -39,6 +39,12 @@ explain (costs off)
select sum(parallel_restricted(unique1)) from tenk1
group by(parallel_restricted(unique1));
+-- test prepared statement
+prepare tenk1_count(integer) As select count((unique1)) from tenk1 where hundred > $1;
+explain (costs off) execute tenk1_count(1);
+execute tenk1_count(1);
+deallocate tenk1_count;
+
-- test parallel plans for queries containing un-correlated subplans.
alter table tenk2 set (parallel_workers = 0);
explain (costs off)