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 '1994-12-01'
	and o_orderdate < cast(date '1994-12-01' + 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=1195705.71..1195705.76 rows=20 width=175) (actual time=28996.761..28996.769 rows=20 loops=1)
   Buffers: shared hit=444814 read=979439 dirtied=1134 written=373
   ->  Sort  (cost=1195705.71..1197120.81 rows=566041 width=175) (actual time=28996.757..28996.761 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=444814 read=979439 dirtied=1134 written=373
         ->  HashAggregate  (cost=1174983.15..1180643.56 rows=566041 width=175) (actual time=28499.601..28843.511 rows=370923 loops=1)
               Buffers: shared hit=444811 read=979439 dirtied=1134 written=373
               ->  Hash Join  (cost=401361.63..1160832.12 rows=566041 width=175) (actual time=5521.583..26116.350 rows=1078878 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=444811 read=979439 dirtied=1134 written=373
                     ->  Hash Join  (cost=401360.07..1153047.50 rows=566041 width=153) (actual time=5521.542..25663.386 rows=1078878 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=444810 read=979439 dirtied=1134 written=373
                           ->  Merge Join  (cost=332332.07..1072698.68 rows=566041 width=12) (actual time=2534.274..20163.783 rows=1078878 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=409535 read=979436 dirtied=1134 written=373
                                 ->  Sort  (cost=332332.03..333763.27 rows=572497 width=8) (actual time=2534.045..2672.277 rows=561126 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 50879kB
                                       Buffers: shared hit=207376 read=24043 written=19
                                       ->  Bitmap Heap Scan on orders  (cost=12434.09..277581.54 rows=572497 width=8) (actual time=424.894..2305.869 rows=561126 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                             Buffers: shared hit=207376 read=24043 written=19
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12290.96 rows=572497 width=0) (actual time=277.513..277.513 rows=568602 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                                   Buffers: shared read=1628 written=3
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..694286.39 rows=15023570 width=12) (actual time=0.096..15224.511 rows=14808163 loops=1)
                                       Buffers: shared hit=202159 read=955393 dirtied=1134 written=354
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2985.033..2985.033 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35275 read=3
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.012..696.637 rows=1500000 loops=1)
                                       Buffers: shared hit=35275 read=3
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.019..0.019 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=0.004..0.008 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 29076.634 ms
(40 rows)

COMMIT;
COMMIT