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 '1993-09-01'
	and o_orderdate < cast(date '1993-09-01' + 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=1148873.59..1148873.64 rows=20 width=175) (actual time=21742.122..21742.129 rows=20 loops=1)
   Buffers: shared hit=801013 read=606283
   ->  Sort  (cost=1148873.59..1150259.44 rows=554343 width=175) (actual time=21742.120..21742.122 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=801013 read=606283
         ->  HashAggregate  (cost=1128579.29..1134122.72 rows=554343 width=175) (actual time=21389.472..21613.495 rows=378567 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=801010 read=606283
               ->  Hash Join  (cost=350982.63..1114720.71 rows=554343 width=175) (actual time=3439.211..19049.570 rows=1135310 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=801010 read=606283
                     ->  Hash Join  (cost=350981.06..1107096.94 rows=554343 width=153) (actual time=3439.177..18696.593 rows=1135310 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=801009 read=606283
                           ->  Hash Join  (cost=281953.06..1029753.79 rows=554343 width=12) (actual time=1938.057..16556.727 rows=1135310 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=801007 read=571007
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686598.50 rows=14842461 width=12) (actual time=0.071..11564.134 rows=14808721 loops=1)
                                       Buffers: shared hit=601747 read=540177
                                 ->  Hash  (cost=274914.82..274914.82 rows=563025 width=8) (actual time=1924.983..1924.983 rows=567366 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30355kB
                                       Buffers: shared hit=199260 read=30830
                                       ->  Bitmap Heap Scan on orders  (cost=11935.44..274914.82 rows=563025 width=8) (actual time=200.533..1687.081 rows=567366 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-09-01'::date) AND (o_orderdate < '1993-12-01'::date))
                                             Heap Blocks: exact=228533
                                             Buffers: shared hit=199260 read=30830
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11794.68 rows=563025 width=0) (actual time=137.052..137.052 rows=570087 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-09-01'::date) AND (o_orderdate < '1993-12-01'::date))
                                                   Buffers: shared read=1557
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1494.949..1494.949 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.005..759.383 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.022..0.022 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..0.009 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 6.641 ms
 Execution time: 21765.313 ms
(42 rows)

COMMIT;
COMMIT