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', '11', '12', '18', '30', '25', '24')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('15', '11', '12', '18', '30', '25', '24')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695197.65..695197.66 rows=3 width=20) (actual time=13563.224..13563.224 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=318494 read=9112
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52833.79..52833.80 rows=1 width=4) (actual time=746.164..746.164 rows=1 loops=1)
           Buffers: shared hit=31981 read=4361
           ->  Bitmap Heap Scan on customer  (cost=6630.87..51883.79 rows=379997 width=4) (actual time=144.644..636.405 rows=381449 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,11,12,18,30,25,24}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=31981 read=4361
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6535.87 rows=379997 width=0) (actual time=132.341..132.341 rows=381449 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{15,11,12,18,30,25,24}'::text[]))
                       Buffers: shared hit=9 read=1055
   ->  HashAggregate  (cost=642363.78..642363.83 rows=3 width=20) (actual time=13563.148..13563.151 rows=7 loops=1)
         Buffers: shared hit=318492 read=9112
         ->  Hash Anti Join  (cost=598987.55..641920.50 rows=59104 width=20) (actual time=12888.880..13525.740 rows=63662 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=318492 read=9112
               ->  Bitmap Heap Scan on customer  (cost=2902.61..41839.42 rows=139383 width=24) (actual time=838.946..1092.245 rows=190459 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,11,12,18,30,25,24}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=63145 read=8908
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2867.77 rows=139383 width=0) (actual time=823.706..823.706 rows=190459 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,11,12,18,30,25,24}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=31991 read=4898
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=12038.762..12038.762 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=255344 read=204
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.024..4949.455 rows=15015000 loops=1)
                           Buffers: shared hit=255344 read=204
 Total runtime: 13684.925 ms
(30 rows)

COMMIT;
COMMIT