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
				('31', '16', '15', '20', '29', '32', '21')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('31', '16', '15', '20', '29', '32', '21')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=699525.08..699525.09 rows=3 width=20) (actual time=20806.102..20806.103 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=320260 read=8625 written=1094
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52984.63..52984.64 rows=1 width=4) (actual time=1189.714..1189.714 rows=1 loops=1)
           Buffers: shared hit=34745 read=1600 written=128
           ->  Bitmap Heap Scan on customer  (cost=6681.83..52025.95 rows=383471 width=4) (actual time=245.465..1061.516 rows=382907 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,16,15,20,29,32,21}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=34745 read=1600 written=128
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6585.97 rows=383471 width=0) (actual time=231.411..231.411 rows=382907 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{31,16,15,20,29,32,21}'::text[]))
                       Buffers: shared hit=11 read=1056 written=81
   ->  HashAggregate  (cost=646540.38..646540.42 rows=3 width=20) (actual time=20806.028..20806.030 rows=7 loops=1)
         Buffers: shared hit=320258 read=8625 written=1094
         ->  Hash Anti Join  (cost=601978.45..646094.34 rows=59472 width=20) (actual time=19608.628..20754.203 rows=63703 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=320258 read=8625 written=1094
               ->  Bitmap Heap Scan on customer  (cost=2942.81..41910.85 rows=140573 width=24) (actual time=1302.918..2009.805 rows=191469 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,16,15,20,29,32,21}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=68488 read=3579 written=180
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2907.67 rows=140573 width=0) (actual time=1290.488..1290.488 rows=191469 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,16,15,20,29,32,21}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=34756 read=2140 written=180
               ->  Hash  (cost=408911.95..408911.95 rows=15209895 width=4) (actual time=18296.904..18296.904 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=251767 read=5046 written=914
                     ->  Seq Scan on orders  (cost=0.00..408911.95 rows=15209895 width=4) (actual time=0.042..9290.139 rows=15000000 loops=1)
                           Buffers: shared hit=251767 read=5046 written=914
 Total runtime: 20915.394 ms
(30 rows)

COMMIT;
COMMIT