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 '1994-01-01'
	and o_orderdate < cast(date '1994-01-01' + 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=1161070.73..1161070.78 rows=20 width=175) (actual time=23558.511..23558.517 rows=20 loops=1)
   Buffers: shared hit=765246 read=662003 dirtied=223 written=4201
   ->  Sort  (cost=1161070.73..1162490.56 rows=567930 width=175) (actual time=23558.508..23558.511 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=765246 read=662003 dirtied=223 written=4201
         ->  HashAggregate  (cost=1140279.02..1145958.32 rows=567930 width=175) (actual time=23204.749..23422.068 rows=375126 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=765243 read=662003 dirtied=223 written=4201
               ->  Hash Join  (cost=353578.50..1126080.77 rows=567930 width=175) (actual time=3996.721..21126.234 rows=1121466 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=765243 read=662003 dirtied=223 written=4201
                     ->  Hash Join  (cost=353576.93..1118270.17 rows=567930 width=153) (actual time=3996.682..20749.861 rows=1121466 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=765242 read=662003 dirtied=223 written=4201
                           ->  Hash Join  (cost=284548.93..1040723.22 rows=567930 width=12) (actual time=2500.047..18557.970 rows=1121466 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=729964 read=662003 dirtied=223 written=4201
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..694153.31 rows=15024564 width=12) (actual time=0.066..12637.015 rows=14822519 loops=1)
                                       Buffers: shared hit=577250 read=583668 dirtied=223 written=4192
                                 ->  Hash  (cost=277375.96..277375.96 rows=573803 width=8) (actual time=2494.693..2494.693 rows=560646 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30093kB
                                       Buffers: shared hit=152714 read=78335 written=9
                                       ->  Bitmap Heap Scan on orders  (cost=12461.92..277375.96 rows=573803 width=8) (actual time=276.159..2304.609 rows=560646 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                             Heap Blocks: exact=229425
                                             Buffers: shared hit=152714 read=78335 written=9
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12318.46 rows=573803 width=0) (actual time=196.244..196.244 rows=566864 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-01-01'::date) AND (o_orderdate < '1994-04-01'::date))
                                                   Buffers: shared read=1624
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1488.734..1488.734 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=145) (actual time=0.014..667.171 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.025..0.025 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=0.005..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.202 ms
 Execution time: 23581.777 ms
(42 rows)

COMMIT;
COMMIT