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 '1995-01-01'
	and o_orderdate < cast(date '1995-01-01' + 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=1145069.16..1145069.21 rows=20 width=175) (actual time=31142.257..31142.262 rows=20 loops=1)
   Buffers: shared hit=1149832 read=254831 written=465
   ->  Sort  (cost=1145069.16..1146441.71 rows=549019 width=175) (actual time=31142.253..31142.255 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=1149832 read=254831 written=465
         ->  HashAggregate  (cost=1124969.77..1130459.96 rows=549019 width=175) (actual time=30644.679..30989.340 rows=354688 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=1149829 read=254831 written=465
               ->  Hash Join  (cost=349666.16..1111244.30 rows=549019 width=175) (actual time=8523.124..28577.497 rows=941021 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=1149829 read=254831 written=465
                     ->  Hash Join  (cost=349664.60..1103693.72 rows=549019 width=153) (actual time=8523.081..28175.277 rows=941021 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=1149828 read=254831 written=465
                           ->  Hash Join  (cost=280636.60..1026430.44 rows=549019 width=12) (actual time=6641.248..25237.935 rows=941021 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=1114654 read=254727 written=465
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..684770.27 rows=14809019 width=12) (actual time=0.042..13289.434 rows=14808323 loops=1)
                                       Buffers: shared hit=968194 read=172527 written=50
                                 ->  Hash  (cost=273677.97..273677.97 rows=556655 width=8) (actual time=6635.606..6635.606 rows=561631 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30131kB
                                       Buffers: shared hit=146460 read=82200 written=415
                                       ->  Bitmap Heap Scan on orders  (cost=11806.15..273677.97 rows=556655 width=8) (actual time=581.961..6276.564 rows=561631 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                             Heap Blocks: exact=227123
                                             Buffers: shared hit=146460 read=82200 written=415
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11666.98 rows=556655 width=0) (actual time=436.275..436.275 rows=562162 loops=1)
                                                   Index Cond: ((o_orderdate >= '1995-01-01'::date) AND (o_orderdate < '1995-04-01'::date))
                                                   Buffers: shared hit=531 read=1006
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1873.305..1873.305 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=35174 read=104
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.024..862.712 rows=1500000 loops=1)
                                       Buffers: shared hit=35174 read=104
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.023..0.023 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=0.007..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.591 ms
 Execution time: 31157.756 ms
(42 rows)

COMMIT;
COMMIT