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 '1993-05-01'
	and o_orderdate < cast(date '1993-05-01' + 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=1185928.87..1185928.92 rows=20 width=175) (actual time=36571.000..36571.008 rows=20 loops=1)
   Buffers: shared hit=879923 read=534189
   ->  Sort  (cost=1185928.87..1187347.99 rows=567647 width=175) (actual time=36570.995..36571.000 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=879923 read=534189
         ->  HashAggregate  (cost=1165147.52..1170823.99 rows=567647 width=175) (actual time=35949.926..36366.690 rows=381689 loops=1)
               Buffers: shared hit=879920 read=534189
               ->  Hash Join  (cost=398771.61..1150956.35 rows=567647 width=175) (actual time=6150.478..31690.137 rows=1148634 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=879920 read=534189
                     ->  Hash Join  (cost=398770.05..1143149.64 rows=567647 width=153) (actual time=6150.419..30956.385 rows=1148634 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=879919 read=534189
                           ->  Merge Join  (cost=329742.05..1062768.70 rows=567647 width=12) (actual time=3674.240..26184.648 rows=1148634 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=845659 read=533171
                                 ->  Sort  (cost=329742.05..331177.70 rows=574262 width=8) (actual time=3674.041..3860.061 rows=574123 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51489kB
                                       Buffers: shared hit=194516 read=35647
                                       ->  Bitmap Heap Scan on orders  (cost=12168.08..274810.01 rows=574262 width=8) (actual time=495.423..3378.297 rows=574123 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-05-01'::date) AND (o_orderdate < '1993-08-01'::date))
                                             Buffers: shared hit=194516 read=35647
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12024.52 rows=574262 width=0) (actual time=338.531..338.531 rows=575263 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-05-01'::date) AND (o_orderdate < '1993-08-01'::date))
                                                   Buffers: shared read=1571
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..687301.92 rows=14871659 width=12) (actual time=0.140..19117.058 rows=14823174 loops=1)
                                       Buffers: shared hit=651143 read=497524
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2473.626..2473.626 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=34260 read=1018
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.019..1119.559 rows=1500000 loops=1)
                                       Buffers: shared hit=34260 read=1018
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.034..0.034 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=0.011..0.016 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 36625.817 ms
(40 rows)

COMMIT;
COMMIT