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 '1994-10-01'
	and o_orderdate < cast(date '1994-10-01' + 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=1180727.89..1180727.94 rows=20 width=176) (actual time=33149.506..33149.514 rows=20 loops=1)
   Buffers: shared hit=1135301 read=274914 dirtied=342 written=1965
   ->  Sort  (cost=1180727.89..1182120.85 rows=557185 width=176) (actual time=33149.504..33149.511 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=1135301 read=274914 dirtied=342 written=1965
         ->  HashAggregate  (cost=1160329.55..1165901.40 rows=557185 width=176) (actual time=32589.822..32992.539 rows=381884 loops=1)
               Buffers: shared hit=1135298 read=274914 dirtied=342 written=1965
               ->  Hash Join  (cost=396915.71..1146399.92 rows=557185 width=176) (actual time=10045.804..29230.964 rows=1150321 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1135298 read=274914 dirtied=342 written=1965
                     ->  Hash Join  (cost=396914.15..1138737.07 rows=557185 width=154) (actual time=10045.752..28633.890 rows=1150321 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1135297 read=274914 dirtied=342 written=1965
                           ->  Merge Join  (cost=327886.15..1058565.37 rows=557185 width=12) (actual time=6699.917..22563.701 rows=1150321 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=1100427 read=274506 dirtied=342 written=1965
                                 ->  Sort  (cost=327886.13..329297.23 rows=564439 width=8) (actual time=6699.623..6860.455 rows=574404 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51502kB
                                       Buffers: shared hit=1570 read=228564 dirtied=228
                                       ->  Bitmap Heap Scan on orders  (cost=11975.39..273963.98 rows=564439 width=8) (actual time=409.954..6353.098 rows=574404 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                             Buffers: shared hit=1570 read=228564 dirtied=228
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11834.29 rows=564439 width=0) (actual time=296.387..296.387 rows=574973 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                                   Buffers: shared hit=1570 read=3
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..685230.16 rows=14822016 width=12) (actual time=0.137..12805.683 rows=14808307 loops=1)
                                       Buffers: shared hit=1098857 read=45942 dirtied=114 written=1965
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=3343.913..3343.913 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=34870 read=408
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.016..1107.132 rows=1500000 loops=1)
                                       Buffers: shared hit=34870 read=408
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.021..0.021 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=0.009..0.012 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 33262.750 ms
(40 rows)

COMMIT;
COMMIT