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=1147567.90..1147567.95 rows=20 width=175) (actual time=23252.528..23252.533 rows=20 loops=1)
   Buffers: shared hit=852134 read=556266 written=946
   ->  Sort  (cost=1147567.90..1148950.91 rows=553204 width=175) (actual time=23252.525..23252.527 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=852134 read=556266 written=946
         ->  HashAggregate  (cost=1127315.31..1132847.35 rows=553204 width=175) (actual time=22890.259..23113.910 rows=371412 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=852131 read=556266 written=946
               ->  Hash Join  (cost=350077.43..1113485.21 rows=553204 width=175) (actual time=3634.355..20132.165 rows=1080451 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=852131 read=556266 written=946
                     ->  Hash Join  (cost=350075.87..1105877.09 rows=553204 width=153) (actual time=3634.304..19756.598 rows=1080451 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=852130 read=556266 written=946
                           ->  Hash Join  (cost=281047.87..1028551.03 rows=553204 width=12) (actual time=2099.180..17525.731 rows=1080451 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=816852 read=556266 written=946
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..686293.12 rows=14847582 width=12) (actual time=0.070..11950.173 rows=14823288 loops=1)
                                       Buffers: shared hit=623332 read=520957 written=946
                                 ->  Hash  (cost=274047.43..274047.43 rows=560000 width=8) (actual time=2093.379..2093.379 rows=561901 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30142kB
                                       Buffers: shared hit=193520 read=35309
                                       ->  Bitmap Heap Scan on orders  (cost=11872.43..274047.43 rows=560000 width=8) (actual time=289.690..1905.158 rows=561901 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1994-12-01'::date) AND (o_orderdate < '1995-03-01'::date))
                                             Heap Blocks: exact=227293
                                             Buffers: shared hit=193520 read=35309
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..11732.43 rows=560000 width=0) (actual time=206.910..206.910 rows=562444 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=1522.151..1522.151 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=35278
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.022..666.255 rows=1500000 loops=1)
                                       Buffers: shared hit=35278
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.033..0.033 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: 4.987 ms
 Execution time: 23279.178 ms
(42 rows)

COMMIT;
COMMIT