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
				('31', '15', '26', '32', '16', '13', '30')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('31', '15', '26', '32', '16', '13', '30')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694225.22..694225.23 rows=3 width=20) (actual time=10434.012..10434.013 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=212063 read=114797 written=96
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52965.88..52965.89 rows=1 width=4) (actual time=560.087..560.087 rows=1 loops=1)
           Buffers: shared hit=20689 read=15655 written=44
           ->  Bitmap Heap Scan on customer customer_1  (cost=6678.70..52008.56 rows=382928 width=4) (actual time=78.259..492.759 rows=382354 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,15,26,32,16,13,30}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=20689 read=15655 written=44
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6582.96 rows=382928 width=0) (actual time=70.909..70.909 rows=382354 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{31,15,26,32,16,13,30}'::text[]))
                       Buffers: shared hit=10 read=1056
   ->  HashAggregate  (cost=641259.27..641259.31 rows=3 width=20) (actual time=10433.946..10433.949 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=212060 read=114797 written=96
         ->  Hash Anti Join  (cost=597251.79..640817.25 rows=58936 width=20) (actual time=9779.763..10411.204 rows=63565 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=212060 read=114797 written=96
               ->  Bitmap Heap Scan on customer  (cost=2941.95..41905.14 rows=140388 width=24) (actual time=610.428..1084.207 rows=191281 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,15,26,32,16,13,30}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35175
                     Buffers: shared hit=20701 read=51366 written=44
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2906.85 rows=140388 width=0) (actual time=603.158..603.158 rows=191281 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{31,15,26,32,16,13,30}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=20699 read=16193 written=44
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=9051.040..9051.040 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=191356 read=63431 written=52
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.026..4279.890 rows=15015000 loops=1)
                           Buffers: shared hit=191356 read=63431 written=52
 Planning time: 2.555 ms
 Execution time: 10457.340 ms
(34 rows)

COMMIT;
COMMIT