1 files changed, 47 insertions, 4 deletions

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 6eeeb0e1d03..72a26695f06 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -3280,10 +3280,53 @@ adjust_group_pathkeys_for_groupagg(PlannerInfo *root)
 		if (AGGKIND_IS_ORDERED_SET(aggref->aggkind))
 			continue;
 
-		/* only add aggregates with a DISTINCT or ORDER BY */
-		if (aggref->aggdistinct != NIL || aggref->aggorder != NIL)
-			unprocessed_aggs = bms_add_member(unprocessed_aggs,
-											  foreach_current_index(lc));
+		/* Skip unless there's a DISTINCT or ORDER BY clause */
+		if (aggref->aggdistinct == NIL && aggref->aggorder == NIL)
+			continue;
+
+		/* Additional safety checks are needed if there's a FILTER clause */
+		if (aggref->aggfilter != NULL)
+		{
+			ListCell   *lc2;
+			bool		allow_presort = true;
+
+			/*
+			 * When the Aggref has a FILTER clause, it's possible that the
+			 * filter removes rows that cannot be sorted because the
+			 * expression to sort by results in an error during its
+			 * evaluation.  This is a problem for presorting as that happens
+			 * before the FILTER, whereas without presorting, the Aggregate
+			 * node will apply the FILTER *before* sorting.  So that we never
+			 * try to sort anything that might error, here we aim to skip over
+			 * any Aggrefs with arguments with expressions which, when
+			 * evaluated, could cause an ERROR.  Vars and Consts are ok. There
+			 * may be more cases that should be allowed, but more thought
+			 * needs to be given.  Err on the side of caution.
+			 */
+			foreach(lc2, aggref->args)
+			{
+				TargetEntry *tle = (TargetEntry *) lfirst(lc2);
+				Expr	   *expr = tle->expr;
+
+				while (IsA(expr, RelabelType))
+					expr = (Expr *) (castNode(RelabelType, expr))->arg;
+
+				/* Common case, Vars and Consts are ok */
+				if (IsA(expr, Var) || IsA(expr, Const))
+					continue;
+
+				/* Unsupported.  Don't try to presort for this Aggref */
+				allow_presort = false;
+				break;
+			}
+
+			/* Skip unsupported Aggrefs */
+			if (!allow_presort)
+				continue;
+		}
+
+		unprocessed_aggs = bms_add_member(unprocessed_aggs,
+										  foreach_current_index(lc));
 	}
 
 	/*