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 '1994-10-01'
	and o_orderdate < cast(date '1994-10-01' + 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=1149824.87..1149824.92 rows=20 width=175) (actual time=26037.390..26037.398 rows=20 loops=1)
   Buffers: shared hit=446796 read=962367
   ->  Sort  (cost=1149824.87..1151253.85 rows=571593 width=175) (actual time=26037.386..26037.392 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=446796 read=962367
         ->  HashAggregate  (cost=1128899.06..1134614.99 rows=571593 width=175) (actual time=25532.005..25893.166 rows=382158 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=446793 read=962367
               ->  Hash Join  (cost=350711.63..1114609.23 rows=571593 width=175) (actual time=4888.784..23656.240 rows=1151430 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=446793 read=962367
                     ->  Hash Join  (cost=350710.07..1106748.27 rows=571593 width=153) (actual time=4888.722..23296.091 rows=1151430 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=446792 read=962367
                           ->  Hash Join  (cost=281682.07..1029146.37 rows=571593 width=12) (actual time=3206.596..20578.596 rows=1151430 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=446790 read=927091
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686076.15 rows=14846041 width=12) (actual time=0.076..12694.672 rows=14822992 loops=1)
                                       Buffers: shared hit=386770 read=756978
                                 ->  Hash  (cost=274455.41..274455.41 rows=578098 width=8) (actual time=3199.027..3199.027 rows=574973 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30652kB
                                       Buffers: shared hit=60020 read=170113
                                       ->  Bitmap Heap Scan on orders  (cost=12261.94..274455.41 rows=578098 width=8) (actual time=226.173..2966.290 rows=574973 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                             Heap Blocks: exact=228561
                                             Buffers: shared hit=60020 read=170113
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12117.41 rows=578098 width=0) (actual time=150.695..150.695 rows=574973 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-10-01'::date) AND (o_orderdate < '1995-01-01'::date))
                                                   Buffers: shared read=1572
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1667.048..1667.048 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=0.009..762.412 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.042..0.042 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=0.010..0.016 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 7.908 ms
 Execution time: 26052.764 ms
(42 rows)

COMMIT;
COMMIT