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 '1994-03-01'
	and o_orderdate < cast(date '1994-03-01' + 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=1198578.43..1198578.48 rows=20 width=175) (actual time=63467.501..63467.509 rows=20 loops=1)
   Buffers: shared hit=1246617 read=189156 dirtied=1745 written=24
   ->  Sort  (cost=1198578.43..1200029.42 rows=580395 width=175) (actual time=63467.497..63467.501 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=1246617 read=189156 dirtied=1745 written=24
         ->  HashAggregate  (cost=1177330.38..1183134.33 rows=580395 width=175) (actual time=62895.352..63292.708 rows=381472 loops=1)
               Buffers: shared hit=1246614 read=189156 dirtied=1745 written=24
               ->  Hash Join  (cost=402680.47..1162820.50 rows=580395 width=175) (actual time=12539.430..59000.205 rows=1148919 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1246614 read=189156 dirtied=1745 written=24
                     ->  Hash Join  (cost=402678.90..1154838.51 rows=580395 width=153) (actual time=12538.113..58106.729 rows=1148919 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1246613 read=189156 dirtied=1745 written=24
                           ->  Merge Join  (cost=333650.90..1074202.61 rows=580395 width=12) (actual time=7596.940..50718.484 rows=1148919 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1246610 read=153881 dirtied=1745 written=24
                                 ->  Sort  (cost=333650.90..335114.77 rows=585548 width=8) (actual time=7596.588..7801.808 rows=573731 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51470kB
                                       Buffers: shared hit=217562 read=14742 dirtied=447 written=3
                                       ->  Bitmap Heap Scan on orders  (cost=12719.86..277557.08 rows=585548 width=8) (actual time=719.524..7298.912 rows=573731 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                             Buffers: shared hit=217562 read=14742 dirtied=447 written=3
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12573.47 rows=585548 width=0) (actual time=598.301..598.301 rows=579410 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-03-01'::date) AND (o_orderdate < '1994-06-01'::date))
                                                   Buffers: shared read=1659
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..694243.00 rows=15031491 width=12) (actual time=0.298..39233.432 rows=14822631 loops=1)
                                       Buffers: shared hit=1029048 read=139139 dirtied=1298 written=21
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=4938.967..4938.967 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=0.014..3507.505 rows=1500000 loops=1)
                                       Buffers: shared hit=3 read=35275
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=1.297..1.297 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=1.262..1.267 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 63520.250 ms
(40 rows)

COMMIT;
COMMIT