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
				('33', '28', '34', '22', '27', '19', '21')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('33', '28', '34', '22', '27', '19', '21')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=696089.00..696089.00 rows=3 width=20) (actual time=15167.753..15167.753 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=285957 read=41669
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52996.89..52996.90 rows=1 width=4) (actual time=839.931..839.931 rows=1 loops=1)
           Buffers: shared hit=30445 read=5899
           ->  Bitmap Heap Scan on customer  (cost=6684.44..52037.37 rows=383807 width=4) (actual time=148.422..717.590 rows=382113 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,28,34,22,27,19,21}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=30445 read=5899
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6588.49 rows=383807 width=0) (actual time=136.173..136.173 rows=382113 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{33,28,34,22,27,19,21}'::text[]))
                       Buffers: shared hit=10 read=1056
   ->  HashAggregate  (cost=643092.03..643092.07 rows=3 width=20) (actual time=15167.670..15167.673 rows=7 loops=1)
         Buffers: shared hit=285955 read=41669
         ->  Hash Anti Join  (cost=599028.54..642647.18 rows=59313 width=20) (actual time=13856.795..15109.734 rows=63505 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=285955 read=41669
               ->  Bitmap Heap Scan on customer  (cost=2943.60..41913.74 rows=140653 width=24) (actual time=952.009..1769.208 rows=190809 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,28,34,22,27,19,21}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=30457 read=41616
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2908.44 rows=140653 width=0) (actual time=938.188..938.188 rows=190809 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,28,34,22,27,19,21}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=30455 read=6435
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=12891.717..12891.717 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=255495 read=53
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.038..5961.457 rows=15015000 loops=1)
                           Buffers: shared hit=255495 read=53
 Total runtime: 15292.627 ms
(30 rows)

COMMIT;
COMMIT