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 '1994-11-01'
	and o_orderdate < cast(date '1994-11-01' + 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=1150843.98..1150844.03 rows=20 width=175) (actual time=27185.493..27185.501 rows=20 loops=1)
   Buffers: shared hit=443604 read=965518
   ->  Sort  (cost=1150843.98..1152280.51 rows=574614 width=175) (actual time=27185.488..27185.495 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=443604 read=965518
         ->  HashAggregate  (cost=1129807.56..1135553.70 rows=574614 width=175) (actual time=26627.782..27035.752 rows=382439 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=443601 read=965518
               ->  Hash Join  (cost=350832.38..1115442.21 rows=574614 width=175) (actual time=4949.632..24778.991 rows=1150347 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=443601 read=965518
                     ->  Hash Join  (cost=350830.82..1107539.71 rows=574614 width=153) (actual time=4949.592..24411.543 rows=1150347 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=443600 read=965518
                           ->  Hash Join  (cost=281802.82..1029892.50 rows=574614 width=12) (actual time=3364.201..21857.905 rows=1150347 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=443598 read=930242
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686613.94 rows=14861343 width=12) (actual time=0.081..13315.623 rows=14822992 loops=1)
                                       Buffers: shared hit=385135 read=758613
                                 ->  Hash  (cost=274545.45..274545.45 rows=580555 width=8) (actual time=3356.685..3356.685 rows=575740 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30682kB
                                       Buffers: shared hit=58463 read=171629
                                       ->  Bitmap Heap Scan on orders  (cost=12315.12..274545.45 rows=580555 width=8) (actual time=234.274..3097.513 rows=575740 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-11-01'::date) AND (o_orderdate < '1995-02-01'::date))
                                             Heap Blocks: exact=228517
                                             Buffers: shared hit=58463 read=171629
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12169.98 rows=580555 width=0) (actual time=155.494..155.494 rows=575740 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-11-01'::date) AND (o_orderdate < '1995-02-01'::date))
                                                   Buffers: shared read=1575
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1578.069..1578.069 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=0.007..785.426 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.025..0.025 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=0.007..0.010 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 7.717 ms
 Execution time: 27198.955 ms
(42 rows)

COMMIT;
COMMIT