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
				('21', '14', '12', '32', '30', '25', '29')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('21', '14', '12', '32', '30', '25', '29')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=699971.79..699971.80 rows=3 width=20) (actual time=20914.681..20914.681 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=231834 read=97284
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52908.85..52908.86 rows=1 width=4) (actual time=2094.271..2094.272 rows=1 loops=1)
           Buffers: shared hit=10 read=36331
           ->  Bitmap Heap Scan on customer  (cost=6646.82..51953.71 rows=382053 width=4) (actual time=213.149..1967.595 rows=381796 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,14,12,32,30,25,29}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=10 read=36331
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6551.31 rows=382053 width=0) (actual time=192.091..192.091 rows=381796 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{21,14,12,32,30,25,29}'::text[]))
                       Buffers: shared hit=7 read=1057
   ->  HashAggregate  (cost=647062.86..647062.91 rows=3 width=20) (actual time=20914.596..20914.598 rows=7 loops=1)
         Buffers: shared hit=231832 read=97284
         ->  Hash Anti Join  (cost=602535.28..646618.47 rows=59252 width=20) (actual time=19944.386..20885.658 rows=63887 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=231832 read=97284
               ->  Bitmap Heap Scan on customer  (cost=2909.50..41863.89 rows=140053 width=24) (actual time=2266.666..2909.064 rows=190758 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,14,12,32,30,25,29}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=22 read=72025
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.49 rows=140053 width=0) (actual time=2244.353..2244.353 rows=190758 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,14,12,32,30,25,29}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=20 read=36870
               ->  Hash  (cost=409314.79..409314.79 rows=15224879 width=4) (actual time=17668.544..17668.544 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=231807 read=25259
                     ->  Seq Scan on orders  (cost=0.00..409314.79 rows=15224879 width=4) (actual time=0.047..7279.377 rows=15015000 loops=1)
                           Buffers: shared hit=231807 read=25259
 Total runtime: 21030.377 ms
(30 rows)

COMMIT;
COMMIT