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 '1994-05-01'
	and o_orderdate < cast(date '1994-05-01' + 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=1196627.82..1196627.87 rows=20 width=176) (actual time=43917.287..43917.295 rows=20 loops=1)
   Buffers: shared hit=599169 read=824922 written=5556
   ->  Sort  (cost=1196627.82..1198079.06 rows=580497 width=176) (actual time=43917.282..43917.289 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=599169 read=824922 written=5556
         ->  HashAggregate  (cost=1175376.03..1181181.00 rows=580497 width=176) (actual time=43434.913..43760.548 rows=381720 loops=1)
               Buffers: shared hit=599166 read=824922 written=5556
               ->  Hash Join  (cost=403030.45..1160863.61 rows=580497 width=176) (actual time=6822.157..39357.340 rows=1149696 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=599166 read=824922 written=5556
                     ->  Hash Join  (cost=403028.89..1152880.21 rows=580497 width=154) (actual time=6822.097..38556.980 rows=1149696 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=599165 read=824922 written=5556
                           ->  Merge Join  (cost=334000.89..1072242.27 rows=580497 width=12) (actual time=4062.753..32936.669 rows=1149696 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=563994 read=824815 written=5556
                                 ->  Sort  (cost=334000.87..335471.02 rows=588058 width=8) (actual time=4062.598..4268.398 rows=574511 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51507kB
                                       Buffers: shared hit=179133 read=53095 written=145
                                       ->  Bitmap Heap Scan on orders  (cost=12773.58..277648.45 rows=588058 width=8) (actual time=770.910..3782.306 rows=574511 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                             Buffers: shared hit=179133 read=53095 written=145
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12626.57 rows=588058 width=0) (actual time=517.340..517.340 rows=580349 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                                   Buffers: shared read=1663
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..692071.24 rows=14969962 width=12) (actual time=0.131..24977.507 rows=14822637 loops=1)
                                       Buffers: shared hit=384861 read=771720 written=5411
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=146) (actual time=2757.004..2757.004 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=35171 read=107
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=146) (actual time=0.021..1087.830 rows=1500000 loops=1)
                                       Buffers: shared hit=35171 read=107
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.031..0.031 rows=25 loops=1)
                           Buckets: 1024  Batches: 1  Memory Usage: 2kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.009..0.017 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 43989.991 ms
(40 rows)

COMMIT;
COMMIT