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 '1994-11-01'
	and o_orderdate < cast(date '1994-11-01' + 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=1196194.82..1196194.87 rows=20 width=175) (actual time=34019.009..34019.015 rows=20 loops=1)
   Buffers: shared hit=639703 read=789903 dirtied=1518 written=35312
   ->  Sort  (cost=1196194.82..1197627.11 rows=572913 width=175) (actual time=34019.005..34019.009 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=639703 read=789903 dirtied=1518 written=35312
         ->  HashAggregate  (cost=1175220.68..1180949.81 rows=572913 width=175) (actual time=33487.866..33843.468 rows=382290 loops=1)
               Buffers: shared hit=639700 read=789903 dirtied=1518 written=35312
               ->  Hash Join  (cost=402551.64..1160897.86 rows=572913 width=175) (actual time=4226.158..30072.929 rows=1150131 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=639700 read=789903 dirtied=1518 written=35312
                     ->  Hash Join  (cost=402550.08..1153018.74 rows=572913 width=153) (actual time=4226.119..29407.291 rows=1150131 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=639699 read=789903 dirtied=1518 written=35312
                           ->  Merge Join  (cost=333522.08..1072532.48 rows=572913 width=12) (actual time=2334.530..25286.950 rows=1150131 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=606024 read=788300 dirtied=1518 written=35312
                                 ->  Sort  (cost=333514.52..334966.88 rows=580944 width=8) (actual time=2334.150..2516.817 rows=575597 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51558kB
                                       Buffers: shared hit=230935 read=1978 written=5
                                       ->  Bitmap Heap Scan on orders  (cost=12620.67..277894.83 rows=580944 width=8) (actual time=342.251..2107.491 rows=575597 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-11-01'::date) AND (o_orderdate < '1995-02-01'::date))
                                             Buffers: shared hit=230935 read=1978 written=5
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12475.43 rows=580944 width=0) (actual time=230.223..230.223 rows=582669 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-11-01'::date) AND (o_orderdate < '1995-02-01'::date))
                                                   Buffers: shared read=1667 written=5
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..692921.98 rows=14984861 width=12) (actual time=0.256..19709.206 rows=14822647 loops=1)
                                       Buffers: shared hit=375089 read=786322 dirtied=1518 written=35307
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1889.377..1889.377 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=33675 read=1603
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.013..798.715 rows=1500000 loops=1)
                                       Buffers: shared hit=33675 read=1603
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.020..0.020 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=0.005..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 34065.119 ms
(40 rows)

COMMIT;
COMMIT