EXPLAIN select c_custkey, c_name, sum(l_extendedprice * (1 - l_discount)) as revenue, c_acctbal, n_name, c_address, c_phone, c_comment from customer, orders, lineitem, nation where c_custkey = o_custkey and l_orderkey = o_orderkey and o_orderdate >= date '1994-05-01' and o_orderdate < date '1994-05-01' + interval '3 months' and l_returnflag = 'R' and c_nationkey = n_nationkey group by c_custkey, c_name, c_acctbal, c_phone, n_name, c_address, c_comment order by revenue desc LIMIT 20;
                                                                                    QUERY PLAN                                                                                    
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 Limit  (cost=2735707.98..2735708.03 rows=20 width=175)
   ->  Sort  (cost=2735707.98..2737177.54 rows=587826 width=175)
         Sort Key: (sum((lineitem.l_extendedprice * (1::double precision - lineitem.l_discount))))
         ->  GroupAggregate  (cost=2698022.66..2720066.14 rows=587826 width=175)
               Group Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
               ->  Sort  (cost=2698022.66..2699492.23 rows=587826 width=175)
                     Sort Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
                     ->  Hash Join  (cost=385610.23..2541230.15 rows=587826 width=175)
                           Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                           ->  Hash Join  (cost=385608.67..2533145.98 rows=587826 width=153)
                                 Hash Cond: (orders.o_custkey = customer.c_custkey)
                                 ->  Hash Join  (cost=284342.03..2384355.18 rows=587826 width=12)
                                       Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                       ->  Seq Scan on lineitem  (cost=0.00..1815233.20 rows=14938478 width=12)
                                             Filter: (l_returnflag = 'R'::bpchar)
                                       ->  Hash  (cost=274658.02..274658.02 rows=590241 width=8)
                                             ->  Bitmap Heap Scan on orders  (cost=12526.41..274658.02 rows=590241 width=8)
                                                   Recheck Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01 00:00:00'::timestamp without time zone))
                                                   ->  Bitmap Index Scan on i_o_orderdate  (cost=0.00..12378.84 rows=590241 width=0)
                                                         Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01 00:00:00'::timestamp without time zone))
                                 ->  Hash  (cost=50285.17..50285.17 rows=1500117 width=145)
                                       ->  Seq Scan on customer  (cost=0.00..50285.17 rows=1500117 width=145)
                           ->  Hash  (cost=1.25..1.25 rows=25 width=30)
                                 ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30)
(24 rows)