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 '1993-03-01'
	and o_orderdate < cast(date '1993-03-01' + 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=1148831.44..1148831.49 rows=20 width=176) (actual time=23883.328..23883.337 rows=20 loops=1)
   Buffers: shared hit=999581 read=418984 dirtied=685 written=5604
   ->  Sort  (cost=1148831.44..1150238.09 rows=562663 width=176) (actual time=23883.323..23883.326 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=999581 read=418984 dirtied=685 written=5604
         ->  HashAggregate  (cost=1128232.55..1133859.18 rows=562663 width=176) (actual time=23318.475..23728.105 rows=381986 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=999578 read=418984 dirtied=685 written=5604
               ->  Hash Join  (cost=350851.98..1114165.97 rows=562663 width=176) (actual time=4851.525..20677.511 rows=1148244 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=999578 read=418984 dirtied=685 written=5604
                     ->  Hash Join  (cost=350850.42..1106427.79 rows=562663 width=154) (actual time=4851.483..20275.000 rows=1148244 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=999577 read=418984 dirtied=685 written=5604
                           ->  Hash Join  (cost=281822.42..1028959.85 rows=562663 width=12) (actual time=3353.413..17964.440 rows=1148244 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=964299 read=418984 dirtied=685 written=5604
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..685901.68 rows=14829214 width=12) (actual time=0.057..10387.091 rows=14808453 loops=1)
                                       Buffers: shared hit=832590 read=320428 dirtied=685 written=398
                                 ->  Hash  (cost=274686.37..274686.37 rows=570849 width=8) (actual time=3347.151..3347.151 rows=573438 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30592kB
                                       Buffers: shared hit=131709 read=98556 written=5206
                                       ->  Bitmap Heap Scan on orders  (cost=12095.64..274686.37 rows=570849 width=8) (actual time=305.136..3063.628 rows=573438 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-03-01'::date) AND (o_orderdate < '1993-06-01'::date))
                                             Heap Blocks: exact=228695
                                             Buffers: shared hit=131709 read=98556 written=5206
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11952.92 rows=570849 width=0) (actual time=223.087..223.087 rows=575079 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-03-01'::date) AND (o_orderdate < '1993-06-01'::date))
                                                   Buffers: shared read=1570 written=81
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=1485.737..1485.737 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.011..629.292 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  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..0.008 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.671 ms
 Execution time: 23917.749 ms
(42 rows)

COMMIT;
COMMIT