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
				('10', '21', '23', '20', '25', '12', '14')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('10', '21', '23', '20', '25', '12', '14')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694103.58..694103.59 rows=3 width=20) (actual time=10760.089..10760.089 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=289535 read=37302 written=16
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52908.61..52908.62 rows=1 width=4) (actual time=817.328..817.328 rows=1 loops=1)
           Buffers: shared hit=10 read=36330 written=16
           ->  Bitmap Heap Scan on customer customer_1  (cost=6647.64..51953.56 rows=382016 width=4) (actual time=92.699..747.721 rows=381568 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{10,21,23,20,25,12,14}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=10 read=36330 written=16
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6552.14 rows=382016 width=0) (actual time=83.921..83.921 rows=381568 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{10,21,23,20,25,12,14}'::text[]))
                       Buffers: shared hit=8 read=1054
   ->  HashAggregate  (cost=641194.90..641194.95 rows=3 width=20) (actual time=10760.017..10760.019 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=289532 read=37302 written=16
         ->  Hash Anti Join  (cost=597220.63..640748.25 rows=59554 width=20) (actual time=10365.486..10739.196 rows=63491 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=289532 read=37302 written=16
               ->  Bitmap Heap Scan on customer  (cost=2910.79..41865.84 rows=140078 width=24) (actual time=879.809..1109.681 rows=190675 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{10,21,23,20,25,12,14}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35157
                     Buffers: shared hit=35177 read=36867 written=16
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.77 rows=140078 width=0) (actual time=871.322..871.322 rows=190675 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{10,21,23,20,25,12,14}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=20 read=36867 written=16
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=9041.069..9041.069 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=254352 read=435
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.018..4407.794 rows=15015000 loops=1)
                           Buffers: shared hit=254352 read=435
 Planning time: 2.828 ms
 Execution time: 10776.185 ms
(34 rows)

COMMIT;
COMMIT