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=1195415.39..1195415.44 rows=20 width=175) (actual time=35299.254..35299.261 rows=20 loops=1)
   Buffers: shared hit=724386 read=705411 dirtied=957 written=2268
   ->  Sort  (cost=1195415.39..1196830.37 rows=565993 width=175) (actual time=35299.249..35299.254 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=724386 read=705411 dirtied=957 written=2268
         ->  HashAggregate  (cost=1174694.59..1180354.52 rows=565993 width=175) (actual time=34831.171..35150.150 rows=378804 loops=1)
               Buffers: shared hit=724383 read=705411 dirtied=957 written=2268
               ->  Hash Join  (cost=401821.85..1160544.76 rows=565993 width=175) (actual time=4869.210..31122.761 rows=1136754 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=724383 read=705411 dirtied=957 written=2268
                     ->  Hash Join  (cost=401820.29..1152760.80 rows=565993 width=153) (actual time=4869.144..30416.768 rows=1136754 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=724382 read=705411 dirtied=957 written=2268
                           ->  Merge Join  (cost=332792.29..1072412.94 rows=565993 width=12) (actual time=3049.606..26350.618 rows=1136754 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=689215 read=705300 dirtied=957 written=2240
                                 ->  Sort  (cost=332784.74..334219.56 rows=573931 width=8) (actual time=3049.375..3239.371 rows=568318 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51216kB
                                       Buffers: shared hit=206264 read=26354 dirtied=221 written=1207
                                       ->  Bitmap Heap Scan on orders  (cost=12464.79..277886.75 rows=573931 width=8) (actual time=382.152..2760.237 rows=568318 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                             Buffers: shared hit=206264 read=26354 dirtied=221 written=1207
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12321.30 rows=573931 width=0) (actual time=232.234..232.234 rows=575707 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                                   Buffers: shared hit=99 read=1548 written=396
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..693599.80 rows=14999536 width=12) (actual time=0.115..19950.918 rows=14822462 loops=1)
                                       Buffers: shared hit=482951 read=678946 dirtied=736 written=1033
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1816.833..1816.833 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35167 read=111 written=28
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.030..794.329 rows=1500000 loops=1)
                                       Buffers: shared hit=35167 read=111 written=28
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.032..0.032 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=0.006..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 35342.593 ms
(40 rows)

COMMIT;
COMMIT