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
				('20', '29', '10', '32', '21', '15', '14')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('20', '29', '10', '32', '21', '15', '14')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=697281.98..697281.99 rows=3 width=20) (actual time=25857.307..25857.309 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=255974 read=72142 dirtied=279 written=14
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=53007.29..53007.30 rows=1 width=4) (actual time=2843.265..2843.265 rows=1 loops=1)
           Buffers: shared hit=13 read=36330 written=12
           ->  Bitmap Heap Scan on customer  (cost=6686.61..52047.05 rows=384093 width=4) (actual time=238.680..2713.562 rows=382490 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,29,10,32,21,15,14}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=13 read=36330 written=12
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6590.59 rows=384093 width=0) (actual time=223.481..223.481 rows=382490 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{20,29,10,32,21,15,14}'::text[]))
                       Buffers: shared hit=10 read=1055
   ->  HashAggregate  (cost=644274.61..644274.66 rows=3 width=20) (actual time=25857.233..25857.236 rows=7 loops=1)
         Buffers: shared hit=255972 read=72142 dirtied=279 written=14
         ->  Hash Anti Join  (cost=600210.47..643825.43 rows=59891 width=20) (actual time=22577.640..25793.250 rows=63719 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=255972 read=72142 dirtied=279 written=14
               ->  Bitmap Heap Scan on customer  (cost=2945.25..41919.51 rows=140810 width=24) (actual time=2996.856..5754.160 rows=191066 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,29,10,32,21,15,14}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=6273 read=65784 written=12
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2910.05 rows=140810 width=0) (actual time=2983.036..2983.036 rows=191066 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,29,10,32,21,15,14}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=23 read=36869 written=12
               ->  Hash  (cost=407703.43..407703.43 rows=15164943 width=4) (actual time=19572.110..19572.110 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=249696 read=6358 dirtied=279 written=2
                     ->  Seq Scan on orders  (cost=0.00..407703.43 rows=15164943 width=4) (actual time=0.045..11457.540 rows=15015000 loops=1)
                           Buffers: shared hit=249696 read=6358 dirtied=279 written=2
 Total runtime: 25985.546 ms
(30 rows)

COMMIT;
COMMIT