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 '1993-07-01'
	and o_orderdate < cast(date '1993-07-01' + 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=1183121.16..1183121.21 rows=20 width=175) (actual time=23336.166..23336.174 rows=20 loops=1)
   Buffers: shared hit=269683 read=1139142
   ->  Sort  (cost=1183121.16..1184542.62 rows=568586 width=175) (actual time=23336.151..23336.156 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=269683 read=1139142
         ->  HashAggregate  (cost=1162305.43..1167991.29 rows=568586 width=175) (actual time=22844.101..23193.869 rows=381780 loops=1)
               Buffers: shared hit=269680 read=1139142
               ->  Hash Join  (cost=398607.52..1148090.78 rows=568586 width=175) (actual time=3817.581..20960.220 rows=1147917 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=269680 read=1139142
                     ->  Hash Join  (cost=398605.96..1140271.16 rows=568586 width=153) (actual time=3817.542..20580.366 rows=1147917 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=269679 read=1139142
                           ->  Merge Join  (cost=329577.96..1059871.44 rows=568586 width=12) (actual time=2406.953..17405.907 rows=1147917 loops=1)
                                 Merge Cond: (orders.o_orderkey = lineitem.l_orderkey)
                                 Buffers: shared hit=269677 read=1103866
                                 ->  Sort  (cost=329570.50..331011.90 rows=576560 width=8) (actual time=2406.786..2538.157 rows=574235 loops=1)
                                       Sort Key: orders.o_orderkey
                                       Sort Method: quicksort  Memory: 51494kB
                                       Buffers: shared hit=37135 read=192660
                                       ->  Bitmap Heap Scan on orders  (cost=12231.64..274402.04 rows=576560 width=8) (actual time=186.797..2226.638 rows=574235 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                             Buffers: shared hit=37135 read=192660
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12087.50 rows=576560 width=0) (actual time=127.314..127.314 rows=574235 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-07-01'::date) AND (o_orderdate < '1993-10-01'::date))
                                                   Buffers: shared read=1572
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.00..684713.99 rows=14807321 width=12) (actual time=0.086..12980.182 rows=14822991 loops=1)
                                       Buffers: shared hit=232542 read=911206
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1409.161..1409.161 rows=1500000 loops=1)
                                 Buckets: 262144  Batches: 1  Memory Usage: 265117kB
                                 Buffers: shared hit=2 read=35276
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.004..650.018 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.027..0.027 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=0.008..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Total runtime: 23359.134 ms
(40 rows)

COMMIT;
COMMIT