BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
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 '1994-04-01'
	and o_orderdate < cast(date '1994-04-01' + interval '3 month' as date)
	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                                                                                                 
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=1196158.13..1196158.18 rows=20 width=175) (actual time=38569.533..38569.542 rows=20 loops=1)
   Buffers: shared hit=667234 read=757676 dirtied=1062 written=20454
   ->  Sort  (cost=1196158.13..1197578.93 rows=568322 width=175) (actual time=38569.527..38569.531 rows=20 loops=1)
         Sort Key: (sum((lineitem.l_extendedprice * (1::double precision - lineitem.l_discount))))
         Sort Method: top-N heapsort  Memory: 30kB
         Buffers: shared hit=667234 read=757676 dirtied=1062 written=20454
         ->  HashAggregate  (cost=1175352.06..1181035.28 rows=568322 width=175) (actual time=38013.650..38364.654 rows=379020 loops=1)
               Buffers: shared hit=667231 read=757676 dirtied=1062 written=20454
               ->  Hash Join  (cost=401702.96..1161144.01 rows=568322 width=175) (actual time=4419.818..34053.627 rows=1138104 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=667231 read=757676 dirtied=1062 written=20454
                     ->  Hash Join  (cost=401701.40..1153328.02 rows=568322 width=153) (actual time=4419.777..33287.259 rows=1138104 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=667230 read=757676 dirtied=1062 written=20454
                           ->  Merge Join  (cost=332673.40..1072933.58 rows=568322 width=12) (actual time=2464.446..28948.528 rows=1138104 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=631956 read=757672 dirtied=1062 written=20454
                                 ->  Sort  (cost=332673.40..334110.75 rows=574943 width=8) (actual time=2464.292..2666.855 rows=568623 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51231kB
                                       Buffers: shared hit=229861 read=2217
                                       ->  Bitmap Heap Scan on orders  (cost=12487.16..277671.30 rows=574943 width=8) (actual time=364.376..2226.325 rows=568623 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                             Buffers: shared hit=229861 read=2217
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12343.42 rows=574943 width=0) (actual time=260.236..260.236 rows=575470 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                                   Buffers: shared read=1648
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..694154.67 rows=15019929 width=12) (actual time=0.111..22990.349 rows=14822607 loops=1)
                                       Buffers: shared hit=402095 read=755455 dirtied=1062 written=20454
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1953.464..1953.464 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35274 read=4
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.011..873.546 rows=1500000 loops=1)
                                       Buffers: shared hit=35274 read=4
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.020..0.020 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 2kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.005..0.007 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 38613.330 ms
(40 rows)

COMMIT;
COMMIT