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=1148962.58..1148962.63 rows=20 width=175) (actual time=29314.204..29314.211 rows=20 loops=1)
   Buffers: shared hit=800491 read=621897 dirtied=775 written=6218
   ->  Sort  (cost=1148962.58..1150350.66 rows=555232 width=175) (actual time=29314.200..29314.205 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=800491 read=621897 dirtied=775 written=6218
         ->  HashAggregate  (cost=1128635.73..1134188.05 rows=555232 width=175) (actual time=28796.430..29157.717 rows=381227 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=800488 read=621897 dirtied=775 written=6218
               ->  Hash Join  (cost=350714.79..1114754.93 rows=555232 width=175) (actual time=5303.786..26617.619 rows=1145797 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=800488 read=621897 dirtied=775 written=6218
                     ->  Hash Join  (cost=350713.23..1107118.93 rows=555232 width=153) (actual time=5303.723..26185.586 rows=1145797 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=800487 read=621897 dirtied=775 written=6218
                           ->  Hash Join  (cost=281685.23..1029762.45 rows=555232 width=12) (actual time=2873.460..22821.669 rows=1145797 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=767217 read=619889 dirtied=775 written=6143
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686824.88 rows=14853454 width=12) (actual time=0.067..15118.468 rows=14808228 loops=1)
                                       Buffers: shared hit=581385 read=574920 dirtied=775 written=4158
                                 ->  Hash  (cost=274647.92..274647.92 rows=562950 width=8) (actual time=2777.785..2777.785 rows=573259 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30585kB
                                       Buffers: shared hit=185832 read=44969 written=1985
                                       ->  Bitmap Heap Scan on orders  (cost=11922.67..274647.92 rows=562950 width=8) (actual time=495.360..2539.548 rows=573259 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-07-01'::date) AND (o_orderdate < '1994-10-01'::date))
                                             Heap Blocks: exact=229231
                                             Buffers: shared hit=185832 read=44969 written=1985
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11781.93 rows=562950 width=0) (actual time=362.772..362.772 rows=575601 loops=1)
                                                   Index Cond: ((o_orderdate >= '1994-07-01'::date) AND (o_orderdate < '1994-10-01'::date))
                                                   Buffers: shared read=1570 written=79
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=2418.265..2418.265 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=33270 read=2008 written=75
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.035..1141.911 rows=1500000 loops=1)
                                       Buffers: shared hit=33270 read=2008 written=75
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.034..0.034 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..0.017 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 7.431 ms
 Execution time: 29346.715 ms
(42 rows)

COMMIT;
COMMIT