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 '1994-04-01'
	and o_orderdate < cast(date '1994-04-01' + 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=1192885.55..1192885.60 rows=20 width=176) (actual time=39078.979..39078.987 rows=20 loops=1)
   Buffers: shared hit=569939 read=855873 dirtied=112 written=29104
   ->  Sort  (cost=1192885.55..1194316.03 rows=572191 width=176) (actual time=39078.975..39078.977 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=569939 read=855873 dirtied=112 written=29104
         ->  HashAggregate  (cost=1171937.84..1177659.75 rows=572191 width=176) (actual time=38397.434..38838.050 rows=378759 loops=1)
               Buffers: shared hit=569936 read=855873 dirtied=112 written=29104
               ->  Hash Join  (cost=401294.27..1157633.07 rows=572191 width=176) (actual time=4405.476..34610.341 rows=1136916 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=569936 read=855873 dirtied=112 written=29104
                     ->  Hash Join  (cost=401292.71..1149763.88 rows=572191 width=154) (actual time=4405.438..33882.421 rows=1136916 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=569935 read=855873 dirtied=112 written=29104
                           ->  Merge Join  (cost=332264.71..1069292.06 rows=572191 width=12) (actual time=2410.931..29602.386 rows=1136916 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=534660 read=855870 dirtied=112 written=29104
                                 ->  Sort  (cost=332264.69..333712.88 rows=579276 width=8) (actual time=2410.776..2600.258 rows=568048 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51204kB
                                       Buffers: shared hit=229455 read=1702
                                       ->  Bitmap Heap Scan on orders  (cost=12579.56..276816.70 rows=579276 width=8) (actual time=411.440..2192.280 rows=568048 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                             Buffers: shared hit=229455 read=1702
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12434.74 rows=579276 width=0) (actual time=301.752..301.752 rows=573228 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                                   Buffers: shared read=1637
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..691034.43 rows=14949859 width=12) (actual time=0.120..23616.989 rows=14807922 loops=1)
                                       Buffers: shared hit=305205 read=854168 dirtied=112 written=29104
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1992.759..1992.759 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=146) (actual time=0.010..881.090 rows=1500000 loops=1)
                                       Buffers: shared hit=35275 read=3
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.016..0.016 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..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 39127.827 ms
(40 rows)

COMMIT;
COMMIT