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
				('12', '25', '13', '32', '16', '21', '28')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('12', '25', '13', '32', '16', '21', '28')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694736.89..694736.89 rows=3 width=20) (actual time=9415.875..9415.876 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=269157 read=57948 dirtied=131 written=240
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52926.61..52926.62 rows=1 width=4) (actual time=421.410..421.410 rows=1 loops=1)
           Buffers: shared hit=35286 read=1056
           ->  Bitmap Heap Scan on customer customer_1  (cost=6651.44..51970.33 rows=382510 width=4) (actual time=97.768..351.092 rows=382258 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,25,13,32,16,21,28}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35286 read=1056
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6555.81 rows=382510 width=0) (actual time=88.818..88.818 rows=382258 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{12,25,13,32,16,21,28}'::text[]))
                       Buffers: shared hit=8 read=1056
   ->  HashAggregate  (cost=641810.20..641810.25 rows=3 width=20) (actual time=9415.832..9415.833 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=269154 read=57948 dirtied=131 written=240
         ->  Hash Anti Join  (cost=597814.84..641367.42 rows=59038 width=20) (actual time=9130.801..9393.696 rows=63411 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=269154 read=57948 dirtied=131 written=240
               ->  Bitmap Heap Scan on customer  (cost=2912.51..41871.87 rows=140242 width=24) (actual time=485.116..635.997 rows=190952 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,25,13,32,16,21,28}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35169
                     Buffers: shared hit=70464 read=1594
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2877.45 rows=140242 width=0) (actual time=476.556..476.556 rows=190952 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,25,13,32,16,21,28}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35295 read=1594
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=8576.284..8576.284 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=198687 read=56354 dirtied=131 written=240
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.012..3926.211 rows=15000000 loops=1)
                           Buffers: shared hit=198687 read=56354 dirtied=131 written=240
 Planning time: 2.247 ms
 Execution time: 9419.642 ms
(34 rows)

COMMIT;
COMMIT