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 '1994-05-01'
	and o_orderdate < cast(date '1994-05-01' + 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=1196147.79..1196147.84 rows=20 width=175) (actual time=34184.192..34184.200 rows=20 loops=1)
   Buffers: shared hit=564068 read=867039 dirtied=225 written=1620
   ->  Sort  (cost=1196147.79..1197596.44 rows=579462 width=175) (actual time=34184.187..34184.192 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=564068 read=867039 dirtied=225 written=1620
         ->  HashAggregate  (cost=1174933.89..1180728.51 rows=579462 width=175) (actual time=33660.039..34027.343 rows=381711 loops=1)
               Buffers: shared hit=564065 read=867039 dirtied=225 written=1620
               ->  Hash Join  (cost=402500.12..1160447.34 rows=579462 width=175) (actual time=6843.674..30317.560 rows=1149666 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=564065 read=867039 dirtied=225 written=1620
                     ->  Hash Join  (cost=402498.55..1152478.18 rows=579462 width=153) (actual time=6843.633..29739.553 rows=1149666 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=564064 read=867039 dirtied=225 written=1620
                           ->  Merge Join  (cost=333470.55..1071860.94 rows=579462 width=12) (actual time=2717.932..23010.422 rows=1149666 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=528885 read=866940 dirtied=225 written=1620
                                 ->  Sort  (cost=333470.52..334935.73 rows=586083 width=8) (actual time=2717.777..2873.821 rows=574485 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51505kB
                                       Buffers: shared hit=229029 read=2973
                                       ->  Bitmap Heap Scan on orders  (cost=12729.34..277321.58 rows=586083 width=8) (actual time=409.652..2174.444 rows=574485 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                             Buffers: shared hit=229029 read=2973
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12582.82 rows=586083 width=0) (actual time=316.683..316.683 rows=579784 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                                   Buffers: shared hit=93 read=1569
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..692219.94 rows=14978802 width=12) (actual time=0.125..17388.353 rows=14822758 loops=1)
                                       Buffers: shared hit=299856 read=863967 dirtied=225 written=1620
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=4123.659..4123.659 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35179 read=99
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.011..977.716 rows=1500000 loops=1)
                                       Buffers: shared hit=35179 read=99
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.025..0.025 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=0.008..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 34271.533 ms
(40 rows)

COMMIT;
COMMIT