3 files changed, 47 insertions, 2 deletions
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c
index 7dc0df52634..dce3095b3f3 100644
--- a/src/backend/utils/adt/numeric.c
+++ b/src/backend/utils/adt/numeric.c
@@ -4054,8 +4054,8 @@ numeric_poly_combine(PG_FUNCTION_ARGS)
 		state1->sumX = state2->sumX;
 		state1->sumX2 = state2->sumX2;
 #else
-		accum_sum_copy(&state2->sumX, &state1->sumX);
-		accum_sum_copy(&state2->sumX2, &state1->sumX2);
+		accum_sum_copy(&state1->sumX, &state2->sumX);
+		accum_sum_copy(&state1->sumX2, &state2->sumX2);
 #endif
 
 		MemoryContextSwitchTo(old_context);
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index 11674a077bc..56d5fbb4fba 100644
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -2054,3 +2054,30 @@ SELECT balk(hundred) FROM tenk1;
 (1 row)
 
 ROLLBACK;
+-- test coverage for aggregate combine/serial/deserial functions
+BEGIN ISOLATION LEVEL REPEATABLE READ;
+SET parallel_setup_cost = 0;
+SET parallel_tuple_cost = 0;
+SET min_parallel_table_scan_size = 0;
+SET max_parallel_workers_per_gather = 4;
+SET enable_indexonlyscan = off;
+-- variance(int4) covers numeric_poly_combine
+-- sum(int8) covers int8_avg_combine
+EXPLAIN (COSTS OFF)
+  SELECT variance(unique1::int4), sum(unique1::int8) FROM tenk1;
+                  QUERY PLAN                  
+----------------------------------------------
+ Finalize Aggregate
+   ->  Gather
+         Workers Planned: 4
+         ->  Partial Aggregate
+               ->  Parallel Seq Scan on tenk1
+(5 rows)
+
+SELECT variance(unique1::int4), sum(unique1::int8) FROM tenk1;
+       variance       |   sum    
+----------------------+----------
+ 8334166.666666666667 | 49995000
+(1 row)
+
+ROLLBACK;
diff --git a/src/test/regress/sql/aggregates.sql b/src/test/regress/sql/aggregates.sql
index 4ead553479c..651ca02536c 100644
--- a/src/test/regress/sql/aggregates.sql
+++ b/src/test/regress/sql/aggregates.sql
@@ -900,3 +900,21 @@ EXPLAIN (COSTS OFF) SELECT balk(hundred) FROM tenk1;
 SELECT balk(hundred) FROM tenk1;
 
 ROLLBACK;
+
+-- test coverage for aggregate combine/serial/deserial functions
+BEGIN ISOLATION LEVEL REPEATABLE READ;
+
+SET parallel_setup_cost = 0;
+SET parallel_tuple_cost = 0;
+SET min_parallel_table_scan_size = 0;
+SET max_parallel_workers_per_gather = 4;
+SET enable_indexonlyscan = off;
+
+-- variance(int4) covers numeric_poly_combine
+-- sum(int8) covers int8_avg_combine
+EXPLAIN (COSTS OFF)
+  SELECT variance(unique1::int4), sum(unique1::int8) FROM tenk1;
+
+SELECT variance(unique1::int4), sum(unique1::int8) FROM tenk1;
+
+ROLLBACK;