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 '1993-04-01'
	and o_orderdate < cast(date '1993-04-01' + 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=1153133.36..1153133.41 rows=20 width=175) (actual time=25389.695..25389.702 rows=20 loops=1)
   Buffers: shared hit=875042 read=548916 dirtied=80 written=497
   ->  Sort  (cost=1153133.36..1154544.13 rows=564307 width=175) (actual time=25389.692..25389.696 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=875042 read=548916 dirtied=80 written=497
         ->  HashAggregate  (cost=1132474.28..1138117.35 rows=564307 width=175) (actual time=25024.095..25246.672 rows=378482 loops=1)
               Group Key: customer.c_custkey, customer.c_name, customer.c_acctbal, customer.c_phone, nation.n_name, customer.c_address, customer.c_comment
               Buffers: shared hit=875039 read=548916 dirtied=80 written=497
               ->  Hash Join  (cost=351767.18..1118366.61 rows=564307 width=175) (actual time=4540.594..23089.864 rows=1135231 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=875039 read=548916 dirtied=80 written=497
                     ->  Hash Join  (cost=351765.62..1110605.83 rows=564307 width=153) (actual time=4540.551..22684.146 rows=1135231 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=875038 read=548916 dirtied=80 written=497
                           ->  Hash Join  (cost=282737.62..1033113.22 rows=564307 width=12) (actual time=2979.962..20408.976 rows=1135231 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=840149 read=548527 dirtied=80 written=495
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..688866.87 rows=14897625 width=12) (actual time=0.074..13975.087 rows=14808418 loops=1)
                                       Buffers: shared hit=698788 read=459635 dirtied=56 written=214
                                 ->  Hash  (cost=275591.57..275591.57 rows=571649 width=8) (actual time=2973.564..2973.564 rows=567616 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30365kB
                                       Buffers: shared hit=141361 read=88892 dirtied=24 written=281
                                       ->  Bitmap Heap Scan on orders  (cost=12203.84..275591.57 rows=571649 width=8) (actual time=299.195..2771.899 rows=567616 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-04-01'::date) AND (o_orderdate < '1993-07-01'::date))
                                             Heap Blocks: exact=228645
                                             Buffers: shared hit=141361 read=88892 dirtied=24 written=281
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12060.92 rows=571649 width=0) (actual time=219.046..219.046 rows=571686 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-04-01'::date) AND (o_orderdate < '1993-07-01'::date))
                                                   Buffers: shared hit=101 read=1507 written=1
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1550.734..1550.734 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=34889 read=389 written=2
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.020..711.629 rows=1500000 loops=1)
                                       Buffers: shared hit=34889 read=389 written=2
                     ->  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: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.006..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.278 ms
 Execution time: 25406.595 ms
(42 rows)

COMMIT;
COMMIT