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=1148331.66..1148331.71 rows=20 width=175) (actual time=26412.331..26412.338 rows=20 loops=1)
   Buffers: shared hit=449097 read=959797
   ->  Sort  (cost=1148331.66..1149758.64 rows=570792 width=175) (actual time=26412.322..26412.322 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=449097 read=959797
         ->  HashAggregate  (cost=1127435.17..1133143.09 rows=570792 width=175) (actual time=26016.545..26279.337 rows=381837 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=449094 read=959797
               ->  Hash Join  (cost=350743.53..1113165.37 rows=570792 width=175) (actual time=4643.889..24116.745 rows=1149931 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=449094 read=959797
                     ->  Hash Join  (cost=350741.97..1105315.42 rows=570792 width=153) (actual time=4643.844..23762.736 rows=1149931 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=449093 read=959797
                           ->  Hash Join  (cost=281713.97..1027725.54 rows=570792 width=12) (actual time=3105.544..20980.487 rows=1149931 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=449091 read=924521
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..684770.27 rows=14809019 width=12) (actual time=0.085..13362.114 rows=14822992 loops=1)
                                       Buffers: shared hit=371863 read=771885
                                 ->  Hash  (cost=274479.39..274479.39 rows=578731 width=8) (actual time=3101.976..3101.976 rows=574622 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30639kB
                                       Buffers: shared hit=77228 read=152636
                                       ->  Bitmap Heap Scan on orders  (cost=12276.43..274479.39 rows=578731 width=8) (actual time=205.020..2840.790 rows=574622 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                             Heap Blocks: exact=228293
                                             Buffers: shared hit=77228 read=152636
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12131.75 rows=578731 width=0) (actual time=143.497..143.497 rows=574622 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-05-01'::date) AND (o_orderdate < '1994-08-01'::date))
                                                   Buffers: shared read=1571
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1529.251..1529.251 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=0.012..779.620 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.026..0.026 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=0.009..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 7.152 ms
 Execution time: 26427.715 ms
(42 rows)

COMMIT;
COMMIT