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 '1994-07-01'
	and o_orderdate < cast(date '1994-07-01' + 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=1154275.20..1154275.25 rows=20 width=175) (actual time=26161.989..26161.995 rows=20 loops=1)
   Buffers: shared hit=901764 read=519788 written=7332
   ->  Sort  (cost=1154275.20..1155683.69 rows=563396 width=175) (actual time=26161.987..26161.989 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=901764 read=519788 written=7332
         ->  HashAggregate  (cost=1133649.48..1139283.44 rows=563396 width=175) (actual time=25598.941..26002.603 rows=381216 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=901761 read=519788 written=7332
               ->  Hash Join  (cost=352036.14..1119564.58 rows=563396 width=175) (actual time=4320.942..23463.956 rows=1146009 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=901761 read=519788 written=7332
                     ->  Hash Join  (cost=352034.58..1111816.32 rows=563396 width=153) (actual time=4320.900..23059.085 rows=1146009 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=901760 read=519788 written=7332
                           ->  Hash Join  (cost=283006.58..1034337.38 rows=563396 width=12) (actual time=2443.935..20095.234 rows=1146009 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=901758 read=484512 written=6088
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..689739.18 rows=14922157 width=12) (actual time=0.056..12849.793 rows=14808293 loops=1)
                                       Buffers: shared hit=706815 read=447897 written=3405
                                 ->  Hash  (cost=275877.43..275877.43 rows=570297 width=8) (actual time=2438.357..2438.357 rows=573362 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30589kB
                                       Buffers: shared hit=194943 read=36615 written=2683
                                       ->  Bitmap Heap Scan on orders  (cost=12281.98..275877.43 rows=570297 width=8) (actual time=298.407..2194.531 rows=573362 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-07-01'::date) AND (o_orderdate < '1994-10-01'::date))
                                             Heap Blocks: exact=229918
                                             Buffers: shared hit=194943 read=36615 written=2683
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12139.41 rows=570297 width=0) (actual time=214.438..214.438 rows=577379 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-07-01'::date) AND (o_orderdate < '1994-10-01'::date))
                                                   Buffers: shared read=1640 written=97
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1864.699..1864.699 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=2 read=35276 written=1244
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.019..945.777 rows=1500000 loops=1)
                                       Buffers: shared hit=2 read=35276 written=1244
                     ->  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=0.009..0.011 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 5.177 ms
 Execution time: 26185.013 ms
(42 rows)

COMMIT;
COMMIT