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', '30', '14', '32', '25', '26', '13')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '30', '14', '32', '25', '26', '13')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694790.93..694790.94 rows=3 width=20) (actual time=17671.502..17671.503 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=194506 read=132589 dirtied=219 written=3647
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52936.16..52936.17 rows=1 width=4) (actual time=1038.520..1038.520 rows=1 loops=1)
           Buffers: shared hit=10 read=36333
           ->  Bitmap Heap Scan on customer  (cost=6652.63..51979.15 rows=382801 width=4) (actual time=136.049..929.531 rows=381664 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,30,14,32,25,26,13}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=10 read=36333
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6556.93 rows=382801 width=0) (actual time=124.104..124.104 rows=381664 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,30,14,32,25,26,13}'::text[]))
                       Buffers: shared hit=8 read=1057
   ->  HashAggregate  (cost=641854.70..641854.74 rows=3 width=20) (actual time=17671.422..17671.425 rows=7 loops=1)
         Buffers: shared hit=194504 read=132589 dirtied=219 written=3647
         ->  Hash Anti Join  (cost=597814.20..641411.01 rows=59158 width=20) (actual time=16854.811..17628.411 rows=63790 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=194504 read=132589 dirtied=219 written=3647
               ->  Bitmap Heap Scan on customer  (cost=2911.87..41872.35 rows=140285 width=24) (actual time=1160.962..1500.306 rows=190697 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,30,14,32,25,26,13}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=34167 read=37882 written=151
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2876.80 rows=140285 width=0) (actual time=1135.213..1135.213 rows=190697 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,30,14,32,25,26,13}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=20 read=36871
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=15673.946..15673.946 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=160334 read=94707 dirtied=219 written=3496
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.042..6979.454 rows=15000000 loops=1)
                           Buffers: shared hit=160334 read=94707 dirtied=219 written=3496
 Total runtime: 17849.517 ms
(30 rows)

COMMIT;
COMMIT