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
				('13', '29', '19', '14', '16', '26', '28')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('13', '29', '19', '14', '16', '26', '28')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693521.58..693521.58 rows=3 width=20) (actual time=16266.652..16266.653 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=250053 read=76552
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52881.45..52881.46 rows=1 width=4) (actual time=1209.451..1209.451 rows=1 loops=1)
           Buffers: shared hit=1550 read=34795
           ->  Bitmap Heap Scan on customer  (cost=6641.02..51928.19 rows=381302 width=4) (actual time=167.695..1086.041 rows=382078 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,29,19,14,16,26,28}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=1550 read=34795
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6545.69 rows=381302 width=0) (actual time=148.363..148.363 rows=382078 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{13,29,19,14,16,26,28}'::text[]))
                       Buffers: shared hit=9 read=1058
   ->  HashAggregate  (cost=640640.05..640640.09 rows=3 width=20) (actual time=16266.573..16266.577 rows=7 loops=1)
         Buffers: shared hit=250051 read=76552
         ->  Hash Anti Join  (cost=596626.83..640198.36 rows=58891 width=20) (actual time=14928.784..16210.613 rows=63399 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=250051 read=76552
               ->  Bitmap Heap Scan on customer  (cost=2907.13..41855.59 rows=139827 width=24) (actual time=1277.484..2108.221 rows=190916 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,29,19,14,16,26,28}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=1562 read=70504
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.18 rows=139827 width=0) (actual time=1268.337..1268.337 rows=190916 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,29,19,14,16,26,28}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=1560 read=35331
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=13639.787..13639.787 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=248486 read=6048
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.029..6133.160 rows=15015000 loops=1)
                           Buffers: shared hit=248486 read=6048
 Total runtime: 16438.991 ms
(30 rows)

COMMIT;
COMMIT