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 '1994-09-01'
	and o_orderdate < cast(date '1994-09-01' + 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=1152410.97..1152411.02 rows=20 width=175) (actual time=25262.354..25262.361 rows=20 loops=1)
   Buffers: shared hit=835925 read=585638 written=591
   ->  Sort  (cost=1152410.97..1153785.97 rows=550002 width=175) (actual time=25262.351..25262.354 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=835925 read=585638 written=591
         ->  HashAggregate  (cost=1132275.59..1137775.61 rows=550002 width=175) (actual time=24845.897..25115.440 rows=378851 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=835922 read=585638 written=591
               ->  Hash Join  (cost=351745.06..1118525.54 rows=550002 width=175) (actual time=4769.035..22825.633 rows=1137101 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=835922 read=585638 written=591
                     ->  Hash Join  (cost=351743.50..1110961.45 rows=550002 width=153) (actual time=4768.950..22417.940 rows=1137101 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=835921 read=585638 written=591
                           ->  Hash Join  (cost=282715.50..1033683.42 rows=550002 width=12) (actual time=2817.685..19738.436 rows=1137101 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=835919 read=550362 written=542
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..689546.95 rows=14912372 width=12) (actual time=0.062..13327.329 rows=14823054 loops=1)
                                       Buffers: shared hit=685338 read=469682 written=465
                                 ->  Hash  (cost=275744.32..275744.32 rows=557659 width=8) (actual time=2811.723..2811.723 rows=568417 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30396kB
                                       Buffers: shared hit=150581 read=80680 written=77
                                       ->  Bitmap Heap Scan on orders  (cost=12084.44..275744.32 rows=557659 width=8) (actual time=317.361..2600.688 rows=568417 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                             Heap Blocks: exact=229628
                                             Buffers: shared hit=150581 read=80680 written=77
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11945.02 rows=557659 width=0) (actual time=231.361..231.361 rows=572378 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-09-01'::date) AND (o_orderdate < '1994-12-01'::date))
                                                   Buffers: shared read=1633 written=1
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1942.649..1942.649 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=2 read=35276 written=49
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.022..1033.259 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276 written=49
                     ->  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: 10kB
                           Buffers: shared hit=1
                           ->  Seq Scan on nation  (cost=0.00..1.25 rows=25 width=30) (actual time=0.008..0.016 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 8.045 ms
 Execution time: 25283.021 ms
(42 rows)

COMMIT;
COMMIT