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', '18', '16', '21', '29', '14', '22')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('15', '18', '16', '21', '29', '14', '22')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695283.39..695283.40 rows=3 width=20) (actual time=10363.286..10363.286 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=234189 read=93175 dirtied=108 written=3227
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52905.60..52905.61 rows=1 width=4) (actual time=781.897..781.897 rows=1 loops=1)
           Buffers: shared hit=13 read=36332 written=41
           ->  Bitmap Heap Scan on customer customer_1  (cost=6646.99..51950.76 rows=381934 width=4) (actual time=87.464..712.370 rows=382573 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,18,16,21,29,14,22}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=13 read=36332 written=41
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6551.51 rows=381934 width=0) (actual time=79.378..79.378 rows=382573 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{15,18,16,21,29,14,22}'::text[]))
                       Buffers: shared hit=10 read=1057
   ->  HashAggregate  (cost=642377.71..642377.76 rows=3 width=20) (actual time=10363.219..10363.222 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=234186 read=93175 dirtied=108 written=3227
         ->  Hash Anti Join  (cost=598405.30..641931.15 rows=59541 width=20) (actual time=9617.956..10337.300 rows=63495 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=234186 read=93175 dirtied=108 written=3227
               ->  Bitmap Heap Scan on customer  (cost=2910.51..41864.77 rows=140048 width=24) (actual time=839.567..1401.878 rows=191067 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,18,16,21,29,14,22}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35170
                     Buffers: shared hit=25 read=72038 written=3224
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.49 rows=140048 width=0) (actual time=831.203..831.203 rows=191067 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,18,16,21,29,14,22}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=23 read=36870 written=41
               ->  Hash  (cost=406494.91..406494.91 rows=15119991 width=4) (actual time=8627.583..8627.583 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=234158 read=21137 dirtied=108 written=3
                     ->  Seq Scan on orders  (cost=0.00..406494.91 rows=15119991 width=4) (actual time=0.023..4203.793 rows=15000000 loops=1)
                           Buffers: shared hit=234158 read=21137 dirtied=108 written=3
 Planning time: 2.876 ms
 Execution time: 10383.569 ms
(34 rows)

COMMIT;
COMMIT