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
				('15', '12', '18', '31', '26', '27', '22')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('15', '12', '18', '31', '26', '27', '22')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695225.69..695225.70 rows=3 width=20) (actual time=29405.878..29405.879 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=239924 read=87446
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52848.07..52848.08 rows=1 width=4) (actual time=3555.141..3555.141 rows=1 loops=1)
           Buffers: shared hit=16 read=36328
           ->  Bitmap Heap Scan on customer  (cost=6633.91..51897.10 rows=380388 width=4) (actual time=300.504..3425.216 rows=381671 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,12,18,31,26,27,22}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=16 read=36328
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6538.81 rows=380388 width=0) (actual time=278.862..278.862 rows=381671 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{15,12,18,31,26,27,22}'::text[]))
                       Buffers: shared hit=8 read=1058
   ->  HashAggregate  (cost=642377.55..642377.59 rows=3 width=20) (actual time=29405.792..29405.793 rows=7 loops=1)
         Buffers: shared hit=239922 read=87446
         ->  Hash Anti Join  (cost=598398.13..641932.70 rows=59313 width=20) (actual time=25703.143..29336.949 rows=63325 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=239922 read=87446
               ->  Bitmap Heap Scan on customer  (cost=2903.33..41841.94 rows=139452 width=24) (actual time=3753.250..6859.661 rows=190764 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,12,18,31,26,27,22}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=30 read=72040
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2868.47 rows=139452 width=0) (actual time=3739.934..3739.934 rows=190764 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,12,18,31,26,27,22}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=25 read=36866
               ->  Hash  (cost=406494.91..406494.91 rows=15119991 width=4) (actual time=21936.120..21936.120 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=239889 read=15406
                     ->  Seq Scan on orders  (cost=0.00..406494.91 rows=15119991 width=4) (actual time=0.031..13727.971 rows=15015000 loops=1)
                           Buffers: shared hit=239889 read=15406
 Total runtime: 29616.727 ms
(30 rows)

COMMIT;
COMMIT