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=1187659.80..1187659.85 rows=20 width=175) (actual time=107649.010..107649.042 rows=20 loops=1)
   Buffers: shared hit=741008 read=673266 written=12566
   ->  Sort  (cost=1187659.80..1189082.90 rows=569241 width=175) (actual time=107649.005..107649.010 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=741008 read=673266 written=12566
         ->  HashAggregate  (cost=1166820.09..1172512.50 rows=569241 width=175) (actual time=107039.146..107474.935 rows=381796 loops=1)
               Buffers: shared hit=741005 read=673266 written=12566
               ->  Hash Join  (cost=398779.07..1152589.07 rows=569241 width=175) (actual time=16276.202..102614.455 rows=1149942 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=741005 read=673266 written=12566
                     ->  Hash Join  (cost=398777.51..1144760.44 rows=569241 width=153) (actual time=16276.160..101594.495 rows=1149942 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=741004 read=673266 written=12566
                           ->  Merge Join  (cost=329749.51..1064347.62 rows=569241 width=12) (actual time=9654.493..91350.465 rows=1149942 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=741001 read=637991 written=12566
                                 ->  Sort  (cost=329749.51..331185.23 rows=574289 width=8) (actual time=9654.354..9930.525 rows=574587 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51510kB
                                       Buffers: shared hit=220141 read=10184
                                       ->  Bitmap Heap Scan on orders  (cost=12172.36..274814.69 rows=574289 width=8) (actual time=807.858..9346.589 rows=574587 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                             Buffers: shared hit=220141 read=10184
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12028.79 rows=574289 width=0) (actual time=677.334..677.334 rows=575785 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                                   Buffers: shared read=1572
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..688754.20 rows=14912704 width=12) (actual time=0.117..77454.555 rows=14823178 loops=1)
                                       Buffers: shared hit=520860 read=627807 written=12566
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=6619.659..6619.659 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=3 read=35275
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.016..3989.585 rows=1500000 loops=1)
                                       Buffers: shared hit=3 read=35275
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.022..0.022 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..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 107754.514 ms
(40 rows)

COMMIT;
COMMIT