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 '1993-04-01'
	and o_orderdate < cast(date '1993-04-01' + 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=1193191.45..1193191.50 rows=20 width=175) (actual time=28872.878..28872.886 rows=20 loops=1)
   Buffers: shared hit=931501 read=497992 dirtied=347 written=8
   ->  Sort  (cost=1193191.45..1194620.51 rows=571624 width=175) (actual time=28872.874..28872.878 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=931501 read=497992 dirtied=347 written=8
         ->  HashAggregate  (cost=1172264.50..1177980.74 rows=571624 width=175) (actual time=28376.810..28718.924 rows=378811 loops=1)
               Buffers: shared hit=931498 read=497992 dirtied=347 written=8
               ->  Hash Join  (cost=401135.11..1157973.90 rows=571624 width=175) (actual time=5581.492..25285.730 rows=1136521 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=931498 read=497992 dirtied=347 written=8
                     ->  Hash Join  (cost=401133.55..1150112.51 rows=571624 width=153) (actual time=5581.449..24773.170 rows=1136521 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=931497 read=497992 dirtied=347 written=8
                           ->  Merge Join  (cost=332105.55..1069652.03 rows=571624 width=12) (actual time=2553.675..19525.832 rows=1136521 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=896219 read=497992 dirtied=347 written=8
                                 ->  Sort  (cost=332105.51..333550.91 rows=578159 width=8) (actual time=2553.489..2693.865 rows=568269 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51214kB
                                       Buffers: shared hit=226623 read=4324 dirtied=231
                                       ->  Bitmap Heap Scan on orders  (cost=12552.11..276772.50 rows=578159 width=8) (actual time=378.465..2303.459 rows=568269 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-04-01'::date) AND (o_orderdate < '1993-07-01'::date))
                                             Buffers: shared hit=226623 read=4324 dirtied=231
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12407.57 rows=578159 width=0) (actual time=273.846..273.846 rows=572878 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-04-01'::date) AND (o_orderdate < '1993-07-01'::date))
                                                   Buffers: shared read=1638
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..691531.27 rows=14963907 width=12) (actual time=0.119..14347.775 rows=14822833 loops=1)
                                       Buffers: shared hit=669596 read=493668 dirtied=116 written=8
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3025.529..3025.529 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.011..796.479 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.026..0.026 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=0.009..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 28942.657 ms
(40 rows)

COMMIT;
COMMIT