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 '1994-12-01'
	and o_orderdate < cast(date '1994-12-01' + 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=1144528.34..1144528.39 rows=20 width=175) (actual time=24271.805..24271.811 rows=20 loops=1)
   Buffers: shared hit=452687 read=954947
   ->  Sort  (cost=1144528.34..1145907.73 rows=551754 width=175) (actual time=24271.802..24271.806 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=452687 read=954947
         ->  HashAggregate  (cost=1124328.83..1129846.37 rows=551754 width=175) (actual time=23751.287..24128.135 rows=371402 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=452684 read=954947
               ->  Hash Join  (cost=349851.53..1110534.98 rows=551754 width=175) (actual time=4462.972..21978.735 rows=1080378 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=452684 read=954947
                     ->  Hash Join  (cost=349849.97..1102946.79 rows=551754 width=153) (actual time=4462.932..21639.915 rows=1080378 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=452683 read=954947
                           ->  Hash Join  (cost=280821.97..1025642.48 rows=551754 width=12) (actual time=3011.600..19576.731 rows=1080378 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=452681 read=919671
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..683865.89 rows=14783340 width=12) (actual time=0.068..12417.385 rows=14822992 loops=1)
                                       Buffers: shared hit=375177 read=768571
                                 ->  Hash  (cost=273816.53..273816.53 rows=560400 width=8) (actual time=3003.503..3003.503 rows=561878 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30141kB
                                       Buffers: shared hit=77504 read=151100
                                       ->  Bitmap Heap Scan on orders  (cost=11888.53..273816.53 rows=560400 width=8) (actual time=218.529..2744.470 rows=561878 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                             Heap Blocks: exact=227068
                                             Buffers: shared hit=77504 read=151100
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11748.43 rows=560400 width=0) (actual time=144.903..144.903 rows=561878 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                                   Buffers: shared read=1536
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1444.108..1444.108 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=0.005..689.435 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.027..0.027 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..0.013 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.812 ms
 Execution time: 24284.305 ms
(42 rows)

COMMIT;
COMMIT