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 '1993-09-01'
	and o_orderdate < cast(date '1993-09-01' + 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=1156855.18..1156855.23 rows=20 width=175) (actual time=30650.910..30650.920 rows=20 loops=1)
   Buffers: shared hit=952736 read=473015 dirtied=1639 written=11446
   ->  Sort  (cost=1156855.18..1158272.58 rows=566957 width=175) (actual time=30650.906..30650.914 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=952736 read=473015 dirtied=1639 written=11446
         ->  HashAggregate  (cost=1136099.09..1141768.66 rows=566957 width=175) (actual time=30107.274..30492.823 rows=378639 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=952733 read=473015 dirtied=1639 written=11446
               ->  Hash Join  (cost=352820.55..1121925.17 rows=566957 width=175) (actual time=4629.701..24396.065 rows=1135414 loops=1)
                     Hash Cond: (customer.c_nationkey = nation.n_nationkey)
                     Buffers: shared hit=952733 read=473015 dirtied=1639 written=11446
                     ->  Hash Join  (cost=352818.99..1114127.95 rows=566957 width=153) (actual time=4629.659..23990.462 rows=1135414 loops=1)
                           Hash Cond: (orders.o_custkey = customer.c_custkey)
                           Buffers: shared hit=952732 read=473015 dirtied=1639 written=11446
                           ->  Hash Join  (cost=283790.99..1036595.59 rows=566957 width=12) (actual time=2892.416..21278.122 rows=1135414 loops=1)
                                 Hash Cond: (lineitem.l_orderkey = orders.o_orderkey)
                                 Buffers: shared hit=945226 read=445243 dirtied=1639 written=11430
                                 ->  Index Scan using lineitem_l_orderkey_idx_l_returnflag on lineitem  (cost=0.43..691069.52 rows=14950919 width=12) (actual time=0.081..13816.756 rows=14807964 loops=1)
                                       Buffers: shared hit=810068 read=349307 dirtied=1298 written=11337
                                 ->  Hash  (cost=276616.34..276616.34 rows=573937 width=8) (actual time=2888.247..2888.247 rows=567457 loops=1)
                                       Buckets: 1048576  Batches: 1  Memory Usage: 30359kB
                                       Buffers: shared hit=135158 read=95936 dirtied=341 written=93
                                       ->  Bitmap Heap Scan on orders  (cost=12459.29..276616.34 rows=573937 width=8) (actual time=290.167..2696.157 rows=567457 loops=1)
                                             Recheck Cond: ((o_orderdate >= '1993-09-01'::date) AND (o_orderdate < '1993-12-01'::date))
                                             Heap Blocks: exact=229458
                                             Buffers: shared hit=135158 read=95936 dirtied=341 written=93
                                             ->  Bitmap Index Scan on orders_o_orderdate_o_orderkey_idx  (cost=0.00..12315.80 rows=573937 width=0) (actual time=212.937..212.937 rows=572397 loops=1)
                                                   Index Cond: ((o_orderdate >= '1993-09-01'::date) AND (o_orderdate < '1993-12-01'::date))
                                                   Buffers: shared read=1636
                           ->  Hash  (cost=50278.00..50278.00 rows=1500000 width=145) (actual time=1729.941..1729.941 rows=1500000 loops=1)
                                 Buckets: 2097152  Batches: 1  Memory Usage: 281501kB
                                 Buffers: shared hit=7506 read=27772 written=16
                                 ->  Seq Scan on customer  (cost=0.00..50278.00 rows=1500000 width=145) (actual time=0.015..884.161 rows=1500000 loops=1)
                                       Buffers: shared hit=7506 read=27772 written=16
                     ->  Hash  (cost=1.25..1.25 rows=25 width=30) (actual time=0.026..0.026 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..0.014 rows=25 loops=1)
                                 Buffers: shared hit=1
 Planning time: 6.035 ms
 Execution time: 30673.312 ms
(42 rows)

COMMIT;
COMMIT