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
				('15', '24', '34', '21', '32', '14', '30')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('15', '24', '34', '21', '32', '14', '30')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694843.51..694843.51 rows=3 width=20) (actual time=22501.169..22501.170 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=278460 read=48628 written=1675
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52957.18..52957.19 rows=1 width=4) (actual time=931.529..931.529 rows=1 loops=1)
           Buffers: shared hit=35293 read=1050
           ->  Bitmap Heap Scan on customer  (cost=6675.98..52000.38 rows=382720 width=4) (actual time=204.285..809.991 rows=382082 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,24,34,21,32,14,30}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35293 read=1050
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6580.30 rows=382720 width=0) (actual time=188.351..188.351 rows=382082 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{15,24,34,21,32,14,30}'::text[]))
                       Buffers: shared hit=15 read=1050
   ->  HashAggregate  (cost=641886.25..641886.29 rows=3 width=20) (actual time=22501.107..22501.109 rows=7 loops=1)
         Buffers: shared hit=278458 read=48628 written=1675
         ->  Hash Anti Join  (cost=597843.71..641438.96 rows=59639 width=20) (actual time=21382.197..22468.816 rows=63605 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=278458 read=48628 written=1675
               ->  Bitmap Heap Scan on customer  (cost=2941.38..41905.85 rows=140437 width=24) (actual time=1101.967..1815.497 rows=190884 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,24,34,21,32,14,30}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35308 read=36734 written=1671
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2906.27 rows=140437 width=0) (actual time=1084.567..1084.567 rows=190884 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,24,34,21,32,14,30}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35306 read=1584
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=20261.877..20261.877 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=243147 read=11894 written=4
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.029..7208.293 rows=15015000 loops=1)
                           Buffers: shared hit=243147 read=11894 written=4
 Total runtime: 22655.991 ms
(30 rows)

COMMIT;
COMMIT