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 '1994-04-01'
	and o_orderdate < cast(date '1994-04-01' + 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=1150143.84..1150143.89 rows=20 width=175) (actual time=25681.007..25681.011 rows=20 loops=1)
   Buffers: shared hit=208804 read=1204100 dirtied=576 written=9501
   ->  Sort  (cost=1150143.84..1151561.57 rows=567091 width=175) (actual time=25681.004..25681.007 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=208804 read=1204100 dirtied=576 written=9501
         ->  HashAggregate  (cost=1129382.84..1135053.75 rows=567091 width=175) (actual time=25320.224..25552.194 rows=379056 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=208801 read=1204100 dirtied=576 written=9501
               ->  Hash Join  (cost=350736.61..1115205.57 rows=567091 width=175) (actual time=3837.983..23029.812 rows=1138175 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=208801 read=1204100 dirtied=576 written=9501
                     ->  Hash Join  (cost=350735.04..1107406.51 rows=567091 width=153) (actual time=3837.948..22664.021 rows=1138175 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=208800 read=1204100 dirtied=576 written=9501
                           ->  Hash Join  (cost=281707.04..1029872.14 rows=567091 width=12) (actual time=2115.834..19833.566 rows=1138175 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=208798 read=1168824 dirtied=576 written=9501
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686766.06 rows=14860950 width=12) (actual time=0.061..12870.458 rows=14823288 loops=1)
                                       Buffers: shared hit=50163 read=1097978 dirtied=116 written=9421
                                 ->  Hash  (cost=274537.35..274537.35 rows=573541 width=8) (actual time=2108.398..2108.398 rows=568697 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30407kB
                                       Buffers: shared hit=158635 read=70846 dirtied=460 written=80
                                       ->  Bitmap Heap Scan on orders  (cost=12159.23..274537.35 rows=573541 width=8) (actual time=242.810..1874.574 rows=568697 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                             Heap Blocks: exact=227926
                                             Buffers: shared hit=158635 read=70846 dirtied=460 written=80
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12015.84 rows=573541 width=0) (actual time=163.792..163.792 rows=569286 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-04-01'::date) AND (o_orderdate < '1994-07-01'::date))
                                                   Buffers: shared hit=65 read=1490
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1705.439..1705.439 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=0.006..730.208 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.024..0.024 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..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 4.115 ms
 Execution time: 25707.459 ms
(42 rows)

COMMIT;
COMMIT