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
				('18', '26', '12', '15', '20', '33', '24')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '26', '12', '15', '20', '33', '24')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=698494.29..698494.29 rows=3 width=20) (actual time=19101.661..19101.661 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=250363 read=78274 dirtied=54 written=6106
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=53018.10..53018.11 rows=1 width=4) (actual time=1446.697..1446.697 rows=1 loops=1)
           Buffers: shared hit=9 read=36336 written=3573
           ->  Bitmap Heap Scan on customer  (cost=6688.94..52057.13 rows=384388 width=4) (actual time=164.325..1318.061 rows=382198 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,26,12,15,20,33,24}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=9 read=36336 written=3573
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6592.84 rows=384388 width=0) (actual time=151.147..151.147 rows=382198 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,26,12,15,20,33,24}'::text[]))
                       Buffers: shared hit=6 read=1061 written=97
   ->  HashAggregate  (cost=645476.11..645476.15 rows=3 width=20) (actual time=19101.570..19101.572 rows=7 loops=1)
         Buffers: shared hit=250361 read=78274 dirtied=54 written=6106
         ->  Hash Anti Join  (cost=601392.25..645030.85 rows=59368 width=20) (actual time=18304.310..19056.849 rows=63618 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=250361 read=78274 dirtied=54 written=6106
               ->  Bitmap Heap Scan on customer  (cost=2946.76..41924.90 rows=140958 width=24) (actual time=1608.138..1959.484 rows=190978 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,26,12,15,20,33,24}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=34195 read=37877 written=3625
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2911.52 rows=140958 width=0) (actual time=1587.139..1587.139 rows=190978 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,26,12,15,20,33,24}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=18 read=36875 written=3625
               ->  Hash  (cost=408509.11..408509.11 rows=15194911 width=4) (actual time=16681.672..16681.672 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=216163 read=40397 dirtied=54 written=2481
                     ->  Seq Scan on orders  (cost=0.00..408509.11 rows=15194911 width=4) (actual time=0.059..7609.096 rows=15000000 loops=1)
                           Buffers: shared hit=216163 read=40397 dirtied=54 written=2481
 Total runtime: 19251.805 ms
(30 rows)

COMMIT;
COMMIT