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=1186417.86..1186417.91 rows=20 width=175) (actual time=103589.960..103589.967 rows=20 loops=1)
   Buffers: shared hit=796258 read=617398 written=5125
   ->  Sort  (cost=1186417.86..1187828.59 rows=564292 width=175) (actual time=103589.956..103589.960 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=796258 read=617398 written=5125
         ->  HashAggregate  (cost=1165759.33..1171402.25 rows=564292 width=175) (actual time=102948.929..103414.619 rows=379022 loops=1)
               Buffers: shared hit=796255 read=617398 written=5125
               ->  Hash Join  (cost=398083.52..1151652.03 rows=564292 width=175) (actual time=13827.800..98532.052 rows=1138173 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=796255 read=617398 written=5125
                     ->  Hash Join  (cost=398081.96..1143891.46 rows=564292 width=153) (actual time=13827.757..97522.218 rows=1138173 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=796254 read=617398 written=5125
                           ->  Merge Join  (cost=329053.96..1063577.62 rows=564292 width=12) (actual time=9181.344..89485.105 rows=1138173 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=760981 read=617393 written=5125
                                 ->  Sort  (cost=329053.96..330477.20 rows=569296 width=8) (actual time=9180.528..9435.741 rows=568662 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51233kB
                                       Buffers: shared hit=224009 read=5700 written=1
                                       ->  Bitmap Heap Scan on orders  (cost=12065.18..274632.62 rows=569296 width=8) (actual time=741.589..8862.212 rows=568662 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                             Buffers: shared hit=224009 read=5700 written=1
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11922.86 rows=569296 width=0) (actual time=624.675..624.675 rows=569855 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                                   Buffers: shared read=1556
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..688754.20 rows=14912704 width=12) (actual time=0.688..76100.304 rows=14823150 loops=1)
                                       Buffers: shared hit=536972 read=611693 written=5124
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=4644.365..4644.365 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35273 read=5
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.015..2117.072 rows=1500000 loops=1)
                                       Buffers: shared hit=35273 read=5
                     ->  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=0.008..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 103684.386 ms
(40 rows)

COMMIT;
COMMIT