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
				('24', '17', '20', '23', '19', '10', '15')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('24', '17', '20', '23', '19', '10', '15')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695276.43..695276.44 rows=3 width=20) (actual time=16274.686..16274.686 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=298761 read=28597 written=7
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52871.03..52871.04 rows=1 width=4) (actual time=1228.803..1228.803 rows=1 loops=1)
           Buffers: shared hit=8358 read=27985
           ->  Bitmap Heap Scan on customer  (cost=6638.79..51918.49 rows=381017 width=4) (actual time=175.747..1102.676 rows=382073 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,17,20,23,19,10,15}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=8358 read=27985
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6543.54 rows=381017 width=0) (actual time=151.979..151.979 rows=382073 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{24,17,20,23,19,10,15}'::text[]))
                       Buffers: shared hit=8 read=1057
   ->  HashAggregate  (cost=642405.32..642405.36 rows=3 width=20) (actual time=16274.602..16274.605 rows=7 loops=1)
         Buffers: shared hit=298759 read=28597 written=7
         ->  Hash Anti Join  (cost=598401.79..641960.01 rows=59374 width=20) (actual time=15404.461..16222.566 rows=63397 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=298759 read=28597 written=7
               ->  Bitmap Heap Scan on customer  (cost=2906.99..41855.05 rows=139812 width=24) (actual time=1335.002..1722.790 rows=190777 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,17,20,23,19,10,15}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=43536 read=28522
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.04 rows=139812 width=0) (actual time=1321.096..1321.096 rows=190777 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,17,20,23,19,10,15}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=8367 read=28522
               ->  Hash  (cost=406494.91..406494.91 rows=15119991 width=4) (actual time=14057.872..14057.872 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=255220 read=75 written=7
                     ->  Seq Scan on orders  (cost=0.00..406494.91 rows=15119991 width=4) (actual time=0.035..6654.864 rows=15000000 loops=1)
                           Buffers: shared hit=255220 read=75 written=7
 Total runtime: 16424.452 ms
(30 rows)

COMMIT;
COMMIT