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 '1993-10-01'
	and o_orderdate < cast(date '1993-10-01' + 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=1183691.46..1183691.51 rows=20 width=176) (actual time=43837.128..43837.138 rows=20 loops=1)
   Buffers: shared hit=560380 read=849454 written=36475
   ->  Sort  (cost=1183691.46..1185104.25 rows=565115 width=176) (actual time=43837.124..43837.131 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=560380 read=849454 written=36475
         ->  HashAggregate  (cost=1163002.81..1168653.96 rows=565115 width=176) (actual time=43233.142..43640.910 rows=381124 loops=1)
               Buffers: shared hit=560377 read=849454 written=36475
               ->  Hash Join  (cost=398276.93..1148874.93 rows=565115 width=176) (actual time=5276.185..37491.676 rows=1147141 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=560377 read=849454 written=36475
                     ->  Hash Join  (cost=398275.37..1141103.04 rows=565115 width=154) (actual time=5276.148..36758.211 rows=1147141 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=560376 read=849454 written=36475
                           ->  Merge Join  (cost=329247.37..1060772.74 rows=565115 width=12) (actual time=2596.627..30979.166 rows=1147141 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=560374 read=814178 written=36475
                                 ->  Sort  (cost=329247.35..330678.52 rows=572469 width=8) (actual time=2596.503..2802.192 rows=573178 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51444kB
                                       Buffers: shared hit=228473 read=1570
                                       ->  Bitmap Heap Scan on orders  (cost=12137.70..274499.74 rows=572469 width=8) (actual time=302.000..2198.923 rows=573178 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-10-01'::date) AND (o_orderdate < '1994-01-01'::date))
                                             Buffers: shared hit=228473 read=1570
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11994.59 rows=572469 width=0) (actual time=222.811..222.811 rows=574279 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-10-01'::date) AND (o_orderdate < '1994-01-01'::date))
                                                   Buffers: shared read=1570
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..685919.65 rows=14836901 width=12) (actual time=0.103..24853.570 rows=14808183 loops=1)
                                       Buffers: shared hit=331901 read=812608 written=36475
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2676.978..2676.978 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.013..1041.210 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.017..0.017 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=0.005..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 43967.299 ms
(40 rows)

COMMIT;
COMMIT