tpch1s=# explain select sum(l_quantity), l_partkey, l_suppkey from lineitem group by l_partkey, l_suppkey;
                                             QUERY PLAN                                              
-----------------------------------------------------------------------------------------------------
 Finalize GroupAggregate  (cost=410884.88..570431.61 rows=600139 width=40)
   Group Key: l_partkey, l_suppkey
   ->  Gather Merge  (cost=410884.88..550927.09 rows=1200278 width=40)
         Workers Planned: 2
         ->  Sort  (cost=409884.86..411385.20 rows=600139 width=40)
               Sort Key: l_partkey, l_suppkey
               ->  Partial HashAggregate  (cost=303953.73..335875.20 rows=600139 width=40)
                     Group Key: l_partkey, l_suppkey
                     Planned Partitions: 64
                     ->  Parallel Seq Scan on lineitem  (cost=0.00..137508.81 rows=2500581 width=13)
(10 rows)