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
				('21', '29', '22', '30', '26', '33', '25')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('21', '29', '22', '30', '26', '33', '25')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694752.20..694752.21 rows=3 width=20) (actual time=16695.638..16695.639 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=304620 read=22501 written=17
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52910.47..52910.48 rows=1 width=4) (actual time=812.808..812.808 rows=1 loops=1)
           Buffers: shared hit=34320 read=2023
           ->  Bitmap Heap Scan on customer  (cost=6647.15..51955.22 rows=382098 width=4) (actual time=164.422..684.833 rows=381738 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,29,22,30,26,33,25}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=34320 read=2023
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6551.62 rows=382098 width=0) (actual time=143.929..143.929 rows=381738 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{21,29,22,30,26,33,25}'::text[]))
                       Buffers: shared hit=11 read=1054
   ->  HashAggregate  (cost=641841.65..641841.70 rows=3 width=20) (actual time=16695.574..16695.578 rows=7 loops=1)
         Buffers: shared hit=304618 read=22501 written=17
         ->  Hash Anti Join  (cost=597813.41..641395.09 rows=59542 width=20) (actual time=15718.938..16638.041 rows=63910 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=304618 read=22501 written=17
               ->  Bitmap Heap Scan on customer  (cost=2911.08..41869.54 rows=140208 width=24) (actual time=939.104..1414.475 rows=190950 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,29,22,30,26,33,25}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=69451 read=2624
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2876.03 rows=140208 width=0) (actual time=917.946..917.946 rows=190950 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,29,22,30,26,33,25}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=34332 read=2561
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=14765.163..14765.163 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=235164 read=19877 written=17
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.019..7095.285 rows=15015000 loops=1)
                           Buffers: shared hit=235164 read=19877 written=17
 Total runtime: 16805.195 ms
(30 rows)

COMMIT;
COMMIT