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
				('28', '22', '12', '27', '21', '14', '26')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('28', '22', '12', '27', '21', '14', '26')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=696469.31..696469.31 rows=3 width=20) (actual time=15764.016..15764.016 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=228887 read=98964 written=150
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52918.20..52918.21 rows=1 width=4) (actual time=527.514..527.514 rows=1 loops=1)
           Buffers: shared hit=35277 read=1064
           ->  Bitmap Heap Scan on customer customer_1  (cost=6649.65..51962.50 rows=382280 width=4) (actual time=91.774..449.728 rows=381274 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,22,12,27,21,14,26}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35277 read=1064
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6554.08 rows=382280 width=0) (actual time=83.281..83.281 rows=381274 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{28,22,12,27,21,14,26}'::text[]))
                       Buffers: shared hit=10 read=1053
   ->  HashAggregate  (cost=643551.02..643551.07 rows=3 width=20) (actual time=15763.960..15763.962 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=228884 read=98964 written=150
         ->  Hash Anti Join  (cost=599584.51..643105.08 rows=59459 width=20) (actual time=15018.943..15739.142 rows=63186 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=228884 read=98964 written=150
               ->  Bitmap Heap Scan on customer  (cost=2909.43..41860.91 rows=139942 width=24) (actual time=595.433..1132.345 rows=190599 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,22,12,27,21,14,26}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35158
                     Buffers: shared hit=35291 read=36753 written=45
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.44 rows=139942 width=0) (actual time=587.025..587.025 rows=190599 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,22,12,27,21,14,26}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35287 read=1599
               ->  Hash  (cost=407300.59..407300.59 rows=15149959 width=4) (actual time=11154.086..11154.086 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=193590 read=62211 written=105
                     ->  Seq Scan on orders  (cost=0.00..407300.59 rows=15149959 width=4) (actual time=0.184..5132.435 rows=15015000 loops=1)
                           Buffers: shared hit=193590 read=62211 written=105
 Planning time: 2.640 ms
 Execution time: 15786.173 ms
(34 rows)

COMMIT;
COMMIT