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
				('25', '16', '19', '34', '23', '29', '24')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('25', '16', '19', '34', '23', '29', '24')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695139.26..695139.27 rows=3 width=20) (actual time=20720.282..20720.283 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=325520 read=1597
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52847.10..52847.11 rows=1 width=4) (actual time=1502.704..1502.705 rows=1 loops=1)
           Buffers: shared hit=35284 read=1059
           ->  Bitmap Heap Scan on customer  (cost=6633.69..51896.20 rows=380362 width=4) (actual time=279.826..1372.588 rows=381683 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,16,19,34,23,29,24}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35284 read=1059
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6538.60 rows=380362 width=0) (actual time=266.102..266.102 rows=381683 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{25,16,19,34,23,29,24}'::text[]))
                       Buffers: shared hit=9 read=1056
   ->  HashAggregate  (cost=642292.08..642292.12 rows=3 width=20) (actual time=20720.206..20720.206 rows=7 loops=1)
         Buffers: shared hit=325518 read=1597
         ->  Hash Anti Join  (cost=597805.44..641849.65 rows=58990 width=20) (actual time=20100.612..20693.688 rows=63414 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=325518 read=1597
               ->  Bitmap Heap Scan on customer  (cost=2903.11..41841.23 rows=139433 width=24) (actual time=1660.118..1891.194 rows=190686 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,16,19,34,23,29,24}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70474 read=1597
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2868.26 rows=139433 width=0) (actual time=1642.586..1642.586 rows=190686 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,16,19,34,23,29,24}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35294 read=1597
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=18428.831..18428.831 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=255041
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.022..9093.158 rows=15015000 loops=1)
                           Buffers: shared hit=255041
 Total runtime: 20851.576 ms
(30 rows)

COMMIT;
COMMIT