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
				('11', '13', '18', '15', '14', '22', '23')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('11', '13', '18', '15', '14', '22', '23')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695843.18..695843.19 rows=3 width=20) (actual time=11821.662..11821.664 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=199383 read=128233 written=16
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52875.19..52875.20 rows=1 width=4) (actual time=782.211..782.211 rows=1 loops=1)
           Buffers: shared hit=14 read=36329
           ->  Bitmap Heap Scan on customer customer_1  (cost=6640.54..51922.44 rows=381101 width=4) (actual time=92.625..712.406 rows=381724 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,13,18,15,14,22,23}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=14 read=36329
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6545.26 rows=381101 width=0) (actual time=83.983..83.983 rows=381724 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{11,13,18,15,14,22,23}'::text[]))
                       Buffers: shared hit=11 read=1054
   ->  HashAggregate  (cost=642967.91..642967.95 rows=3 width=20) (actual time=11821.611..11821.612 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=199380 read=128233 written=16
         ->  Hash Anti Join  (cost=598993.43..642527.76 rows=58686 width=20) (actual time=11454.047..11801.565 rows=63238 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=199380 read=128233 written=16
               ->  Bitmap Heap Scan on customer  (cost=2908.50..41857.56 rows=139850 width=24) (actual time=844.787..1067.348 rows=190466 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,13,18,15,14,22,23}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35174
                     Buffers: shared hit=34608 read=37454
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2873.53 rows=139850 width=0) (actual time=836.130..836.130 rows=190466 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,13,18,15,14,22,23}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=25 read=36863
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=10465.845..10465.845 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=164769 read=90779 written=16
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.021..5023.908 rows=15015000 loops=1)
                           Buffers: shared hit=164769 read=90779 written=16
 Planning time: 2.988 ms
 Execution time: 11834.746 ms
(34 rows)

COMMIT;
COMMIT