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
				('24', '27', '20', '18', '25', '21', '32')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('24', '27', '20', '18', '25', '21', '32')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=697155.36..697155.37 rows=3 width=20) (actual time=12123.698..12123.698 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=221261 read=106857 dirtied=62 written=56
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52945.44..52945.45 rows=1 width=4) (actual time=793.260..793.260 rows=1 loops=1)
           Buffers: shared hit=12 read=36327 written=41
           ->  Bitmap Heap Scan on customer customer_1  (cost=6674.36..51989.52 rows=382368 width=4) (actual time=91.824..722.844 rows=381648 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,27,20,18,25,21,32}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=12 read=36327 written=41
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6578.76 rows=382368 width=0) (actual time=83.212..83.212 rows=381648 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{24,27,20,18,25,21,32}'::text[]))
                       Buffers: shared hit=10 read=1052
   ->  HashAggregate  (cost=644209.84..644209.89 rows=3 width=20) (actual time=12123.640..12123.643 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=221258 read=106857 dirtied=62 written=56
         ->  Hash Anti Join  (cost=600206.45..643768.23 rows=58881 width=20) (actual time=11536.427..12100.395 rows=63683 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=221258 read=106857 dirtied=62 written=56
               ->  Bitmap Heap Scan on customer  (cost=2941.23..41902.50 rows=140315 width=24) (actual time=858.520..1285.583 rows=190564 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,27,20,18,25,21,32}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35172
                     Buffers: shared hit=12031 read=60027 written=54
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2906.15 rows=140315 width=0) (actual time=849.420..849.420 rows=190564 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,27,20,18,25,21,32}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=23 read=36863 written=41
               ->  Hash  (cost=407703.43..407703.43 rows=15164943 width=4) (actual time=9952.240..9952.240 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=209224 read=46830 dirtied=62 written=2
                     ->  Seq Scan on orders  (cost=0.00..407703.43 rows=15164943 width=4) (actual time=0.035..4693.099 rows=15015000 loops=1)
                           Buffers: shared hit=209224 read=46830 dirtied=62 written=2
 Planning time: 2.853 ms
 Execution time: 12139.825 ms
(34 rows)

COMMIT;
COMMIT