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
				('18', '26', '13', '17', '12', '34', '30')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '26', '13', '17', '12', '34', '30')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695266.81..695266.82 rows=3 width=20) (actual time=18540.395..18540.397 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=323356 read=3757 dirtied=254 written=549
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52919.29..52919.30 rows=1 width=4) (actual time=1250.501..1250.502 rows=1 loops=1)
           Buffers: shared hit=33458 read=2886 written=488
           ->  Bitmap Heap Scan on customer  (cost=6649.05..51963.44 rows=382339 width=4) (actual time=244.639..1116.850 rows=381763 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,26,13,17,12,34,30}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=33458 read=2886 written=488
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6553.46 rows=382339 width=0) (actual time=224.784..224.784 rows=381763 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,26,13,17,12,34,30}'::text[]))
                       Buffers: shared hit=9 read=1057 written=158
   ->  HashAggregate  (cost=642347.44..642347.48 rows=3 width=20) (actual time=18540.325..18540.329 rows=7 loops=1)
         Buffers: shared hit=323354 read=3757 dirtied=254 written=549
         ->  Hash Anti Join  (cost=597812.91..641902.72 rows=59296 width=20) (actual time=17610.446..18488.760 rows=63771 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323354 read=3757 dirtied=254 written=549
               ->  Bitmap Heap Scan on customer  (cost=2910.58..41867.72 rows=140158 width=24) (actual time=1429.292..1939.840 rows=190819 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,26,13,17,12,34,30}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=68642 read=3425 written=549
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.54 rows=140158 width=0) (actual time=1411.987..1411.987 rows=190819 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,26,13,17,12,34,30}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=33468 read=3424 written=549
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=16169.810..16169.810 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=254709 read=332 dirtied=254
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.020..7824.742 rows=15015000 loops=1)
                           Buffers: shared hit=254709 read=332 dirtied=254
 Total runtime: 18623.226 ms
(30 rows)

COMMIT;
COMMIT