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
				('28', '10', '15', '26', '18', '19', '16')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('28', '10', '15', '26', '18', '19', '16')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694901.93..694901.94 rows=3 width=20) (actual time=16577.847..16577.848 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=288600 read=38503 written=42
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52989.66..52989.67 rows=1 width=4) (actual time=1112.995..1112.995 rows=1 loops=1)
           Buffers: shared hit=11 read=36335 written=42
           ->  Bitmap Heap Scan on customer  (cost=6682.87..52030.63 rows=383610 width=4) (actual time=147.863..994.495 rows=382644 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,10,15,26,18,19,16}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=11 read=36335 written=42
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6586.96 rows=383610 width=0) (actual time=134.936..134.936 rows=382644 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{28,10,15,26,18,19,16}'::text[]))
                       Buffers: shared hit=9 read=1059
   ->  HashAggregate  (cost=641912.20..641912.24 rows=3 width=20) (actual time=16577.770..16577.773 rows=7 loops=1)
         Buffers: shared hit=288598 read=38503 written=42
         ->  Hash Anti Join  (cost=597846.14..641467.84 rows=59248 width=20) (actual time=16027.420..16551.302 rows=63393 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=288598 read=38503 written=42
               ->  Bitmap Heap Scan on customer  (cost=2943.81..41914.48 rows=140673 width=24) (actual time=1218.103..1416.873 rows=191172 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,10,15,26,18,19,16}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35185 read=36872 written=42
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2908.65 rows=140673 width=0) (actual time=1204.679..1204.679 rows=191172 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,10,15,26,18,19,16}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=21 read=36872 written=42
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=14796.122..14796.122 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=253410 read=1631
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.032..6246.140 rows=15015000 loops=1)
                           Buffers: shared hit=253410 read=1631
 Total runtime: 16683.986 ms
(30 rows)

COMMIT;
COMMIT