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 '1994-09-01'
	and o_orderdate < cast(date '1994-09-01' + 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=1145772.31..1145772.36 rows=20 width=176) (actual time=27356.305..27356.309 rows=20 loops=1)
   Buffers: shared hit=666545 read=742182 dirtied=342 written=15612
   ->  Sort  (cost=1145772.31..1147176.98 rows=561868 width=176) (actual time=27356.303..27356.306 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=666545 read=742182 dirtied=342 written=15612
         ->  HashAggregate  (cost=1125202.52..1130821.20 rows=561868 width=176) (actual time=26919.341..27216.435 rows=378505 loops=1)
               Group Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
               Buffers: shared hit=666542 read=742182 dirtied=342 written=15612
               ->  Hash Join  (cost=350365.91..1111155.82 rows=561868 width=176) (actual time=6141.277..24703.936 rows=1135709 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=666542 read=742182 dirtied=342 written=15612
                     ->  Hash Join  (cost=350364.35..1103428.58 rows=561868 width=154) (actual time=6141.233..24329.646 rows=1135709 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=666541 read=742182 dirtied=342 written=15612
                           ->  Hash Join  (cost=281336.35..1025972.56 rows=561868 width=12) (actual time=4613.417..21854.298 rows=1135709 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=632396 read=741049 dirtied=342 written=15612
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..683607.70 rows=14776072 width=12) (actual time=0.123..12414.667 rows=14808323 loops=1)
                                       Buffers: shared hit=605335 read=538520 dirtied=114 written=15612
                                 ->  Hash  (cost=274199.00..274199.00 rows=570953 width=8) (actual time=4605.750..4605.750 rows=567783 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30372kB
                                       Buffers: shared hit=27061 read=202529 dirtied=228
                                       ->  Bitmap Heap Scan on orders  (cost=12112.70..274199.00 rows=570953 width=8) (actual time=265.104..4288.323 rows=567783 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                             Heap Blocks: exact=228035
                                             Buffers: shared hit=27061 read=202529 dirtied=228
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11969.96 rows=570953 width=0) (actual time=183.483..183.483 rows=568340 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                                   Buffers: shared hit=1 read=1554
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1517.880..1517.880 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=34145 read=1133
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.010..582.231 rows=1500000 loops=1)
                                       Buffers: shared hit=34145 read=1133
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.024..0.024 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.007..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 7.074 ms
 Execution time: 27388.763 ms
(42 rows)

COMMIT;
COMMIT