BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
select
	cntrycode,
	count(*) as numcust,
	sum(c_acctbal) as totacctbal
from
	(
		select
			substr(c_phone, 1, 2) as cntrycode,
			c_acctbal
		from
			customer
		where
			substr(c_phone, 1, 2) in
				('26', '28', '14', '18', '17', '31', '15')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('26', '28', '14', '18', '17', '31', '15')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695391.23..695391.24 rows=3 width=20) (actual time=10090.188..10090.188 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=258764 read=68589 written=56
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52961.96..52961.97 rows=1 width=4) (actual time=720.027..720.027 rows=1 loops=1)
           Buffers: shared hit=11 read=36333 written=25
           ->  Bitmap Heap Scan on customer customer_1  (cost=6677.88..52004.91 rows=382820 width=4) (actual time=88.336..652.601 rows=382312 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,28,14,18,17,31,15}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=11 read=36333 written=25
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6582.18 rows=382820 width=0) (actual time=79.988..79.988 rows=382312 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{26,28,14,18,17,31,15}'::text[]))
                       Buffers: shared hit=9 read=1057 written=6
   ->  HashAggregate  (cost=642429.19..642429.24 rows=3 width=20) (actual time=10090.125..10090.126 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=258761 read=68589 written=56
         ->  Hash Anti Join  (cost=598436.60..641981.60 rows=59679 width=20) (actual time=9760.387..10070.434 rows=63445 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=258761 read=68589 written=56
               ->  Bitmap Heap Scan on customer  (cost=2941.81..41904.60 rows=140373 width=24) (actual time=774.285..972.934 rows=191072 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,28,14,18,17,31,15}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35162
                     Buffers: shared hit=34654 read=37398 written=25
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2906.71 rows=140373 width=0) (actual time=766.438..766.438 rows=191072 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,28,14,18,17,31,15}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=21 read=36869 written=25
               ->  Hash  (cost=406494.91..406494.91 rows=15119991 width=4) (actual time=8889.450..8889.450 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=224104 read=31191 written=31
                     ->  Seq Scan on orders  (cost=0.00..406494.91 rows=15119991 width=4) (actual time=0.019..4395.986 rows=15015000 loops=1)
                           Buffers: shared hit=224104 read=31191 written=31
 Planning time: 2.861 ms
 Execution time: 10109.909 ms
(34 rows)

COMMIT;
COMMIT