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
				('29', '22', '20', '21', '30', '15', '17')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('29', '22', '20', '21', '30', '15', '17')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691169.49..691169.50 rows=3 width=20) (actual time=9052.955..9052.956 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=323998 read=1593
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52884.26..52884.27 rows=1 width=4) (actual time=431.882..431.882 rows=1 loops=1)
           Buffers: shared hit=35288 read=1056
           ->  Bitmap Heap Scan on customer  (cost=6641.61..51930.81 rows=381379 width=4) (actual time=94.400..357.156 rows=382336 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,22,20,21,30,15,17}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35288 read=1056
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6546.27 rows=381379 width=0) (actual time=86.065..86.065 rows=382336 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{29,22,20,21,30,15,17}'::text[]))
                       Buffers: shared hit=10 read=1056
   ->  HashAggregate  (cost=638285.15..638285.20 rows=3 width=20) (actual time=9052.842..9052.844 rows=7 loops=1)
         Buffers: shared hit=323996 read=1593
         ->  Hash Anti Join  (cost=594267.78..637840.87 rows=59238 width=20) (actual time=8738.454..9033.121 rows=63921 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323996 read=1593
               ->  Bitmap Heap Scan on customer  (cost=2908.64..41860.98 rows=139975 width=24) (actual time=485.532..588.980 rows=191180 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,22,20,21,30,15,17}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70471 read=1593
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2873.65 rows=139975 width=0) (actual time=478.172..478.172 rows=191180 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{29,22,20,21,30,15,17}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35299 read=1593
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=8245.652..8245.652 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=253522
                     ->  Seq Scan on orders  (cost=0.00..403671.84 rows=15014984 width=4) (actual time=0.019..4445.907 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Total runtime: 9100.237 ms
(30 rows)

COMMIT;
COMMIT