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 '1994-06-01'
	and o_orderdate < cast(date '1994-06-01' + 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=1182967.87..1182967.92 rows=20 width=175) (actual time=43424.372..43424.380 rows=20 loops=1)
   Buffers: shared hit=601317 read=808436 written=38378
   ->  Sort  (cost=1182967.87..1184367.08 rows=559687 width=175) (actual time=43424.368..43424.372 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=601317 read=808436 written=38378
         ->  HashAggregate  (cost=1162477.93..1168074.80 rows=559687 width=175) (actual time=42830.753..43223.782 rows=381802 loops=1)
               Buffers: shared hit=601314 read=808436 written=38378
               ->  Hash Join  (cost=397407.14..1148485.75 rows=559687 width=175) (actual time=5635.841..38802.784 rows=1148552 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=601314 read=808436 written=38378
                     ->  Hash Join  (cost=397405.58..1140788.49 rows=559687 width=153) (actual time=5635.774..37967.351 rows=1148552 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=601313 read=808436 written=38378
                           ->  Merge Join  (cost=328377.58..1060566.75 rows=559687 width=12) (actual time=2411.209..31439.632 rows=1148552 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=601300 read=773171 written=38378
                                 ->  Sort  (cost=328377.58..329793.10 rows=566208 width=8) (actual time=2411.100..2635.253 rows=574219 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51493kB
                                       Buffers: shared hit=228521 read=1573
                                       ->  Bitmap Heap Scan on orders  (cost=12005.53..274273.65 rows=566208 width=8) (actual time=429.333..2143.563 rows=574219 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                             Buffers: shared hit=228521 read=1573
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11863.98 rows=566208 width=0) (actual time=337.373..337.373 rows=575423 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-06-01'::date) AND (o_orderdate < '1994-09-01'::date))
                                                   Buffers: shared read=1573
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..686621.26 rows=14856879 width=12) (actual time=0.082..25276.546 rows=14808169 loops=1)
                                       Buffers: shared hit=372779 read=771598 written=38378
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=3221.118..3221.118 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=13 read=35265
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.023..1231.868 rows=1500000 loops=1)
                                       Buffers: shared hit=13 read=35265
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.036..0.036 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=0.012..0.019 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 43531.296 ms
(40 rows)

COMMIT;
COMMIT