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=1198485.36..1198485.41 rows=20 width=176) (actual time=49357.709..49357.718 rows=20 loops=1)
   Buffers: shared hit=748578 read=677085 dirtied=235 written=209
   ->  Sort  (cost=1198485.36..1199922.94 rows=575035 width=176) (actual time=49357.705..49357.710 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=748578 read=677085 dirtied=235 written=209
         ->  HashAggregate  (cost=1177433.53..1183183.88 rows=575035 width=176) (actual time=48758.476..49189.827 rows=378972 loops=1)
               Buffers: shared hit=748575 read=677085 dirtied=235 written=209
               ->  Hash Join  (cost=402962.96..1163057.66 rows=575035 width=176) (actual time=9447.810..42990.681 rows=1138040 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=748575 read=677085 dirtied=235 written=209
                     ->  Hash Join  (cost=402961.40..1155149.36 rows=575035 width=154) (actual time=9447.748..42205.588 rows=1138040 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=748574 read=677085 dirtied=235 written=209
                           ->  Merge Join  (cost=333933.40..1074620.66 rows=575035 width=12) (actual time=5133.416..34937.387 rows=1138040 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=713416 read=676965 dirtied=235 written=205
                                 ->  Sort  (cost=333933.38..335388.74 rows=582144 width=8) (actual time=5133.204..5335.749 rows=568587 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51229kB
                                       Buffers: shared hit=130464 read=101849 dirtied=235 written=29
                                       ->  Bitmap Heap Scan on orders  (cost=12644.97..278190.13 rows=582144 width=8) (actual time=414.916..4761.483 rows=568587 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                             Buffers: shared hit=130464 read=101849 dirtied=235 written=29
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12499.43 rows=582144 width=0) (actual time=325.719..325.719 rows=576045 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                                   Buffers: shared hit=94 read=1554 written=6
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..694465.80 rows=15024165 width=12) (actual time=0.140..26026.884 rows=14822420 loops=1)
                                       Buffers: shared hit=582952 read=575116 written=176
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=4312.711..4312.711 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35158 read=120 written=4
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.011..1391.377 rows=1500000 loops=1)
                                       Buffers: shared hit=35158 read=120 written=4
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.037..0.037 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=0.025..0.029 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 49457.240 ms
(40 rows)

COMMIT;
COMMIT