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
				('34', '33', '26', '13', '11', '20', '31')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('34', '33', '26', '13', '11', '20', '31')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694091.01..694091.02 rows=3 width=20) (actual time=17738.818..17738.819 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=270602 read=56240
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52869.47..52869.48 rows=1 width=4) (actual time=903.861..903.861 rows=1 loops=1)
           Buffers: shared hit=35284 read=1059
           ->  Bitmap Heap Scan on customer  (cost=6638.47..51917.03 rows=380974 width=4) (actual time=204.975..757.520 rows=381730 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,33,26,13,11,20,31}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35284 read=1059
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6543.22 rows=380974 width=0) (actual time=185.306..185.306 rows=381730 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{34,33,26,13,11,20,31}'::text[]))
                       Buffers: shared hit=8 read=1057
   ->  HashAggregate  (cost=641221.46..641221.50 rows=3 width=20) (actual time=17738.725..17738.727 rows=7 loops=1)
         Buffers: shared hit=270600 read=56240
         ->  Hash Anti Join  (cost=597215.75..640780.15 rows=58841 width=20) (actual time=17129.879..17713.968 rows=63646 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=270600 read=56240
               ->  Bitmap Heap Scan on customer  (cost=2905.91..41851.22 rows=139707 width=24) (actual time=1012.532..1247.943 rows=190895 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,33,26,13,11,20,31}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70452 read=1598
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2870.99 rows=139707 width=0) (actual time=999.296..999.296 rows=190895 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,33,26,13,11,20,31}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35293 read=1598
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=16105.886..16105.886 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=200145 read=54642
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.033..6972.988 rows=15015000 loops=1)
                           Buffers: shared hit=200145 read=54642
 Total runtime: 17872.423 ms
(30 rows)

COMMIT;
COMMIT