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
				('22', '27', '17', '21', '14', '28', '20')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('22', '27', '17', '21', '14', '28', '20')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695270.57..695270.58 rows=3 width=20) (actual time=9053.492..9053.493 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=221243 read=106128 written=8
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52892.60..52892.61 rows=1 width=4) (actual time=500.559..500.560 rows=1 loops=1)
           Buffers: shared hit=23311 read=13030
           ->  Bitmap Heap Scan on customer customer_1  (cost=6644.23..51938.65 rows=381578 width=4) (actual time=94.417..429.052 rows=381673 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{22,27,17,21,14,28,20}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=23311 read=13030
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6548.83 rows=381578 width=0) (actual time=85.765..85.765 rows=381673 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{22,27,17,21,14,28,20}'::text[]))
                       Buffers: shared hit=10 read=1053
   ->  HashAggregate  (cost=642377.90..642377.94 rows=3 width=20) (actual time=9053.448..9053.448 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=221240 read=106128 written=8
         ->  Hash Anti Join  (cost=598403.80..641936.19 rows=58894 width=20) (actual time=8430.245..9025.550 rows=63457 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=221240 read=106128 written=8
               ->  Bitmap Heap Scan on customer  (cost=2909.00..41859.37 rows=139900 width=24) (actual time=564.374..1038.566 rows=190747 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{22,27,17,21,14,28,20}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35183
                     Buffers: shared hit=26903 read=45167 written=1
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.02 rows=139900 width=0) (actual time=555.785..555.785 rows=190747 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{22,27,17,21,14,28,20}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=23322 read=13565
               ->  Hash  (cost=406494.91..406494.91 rows=15119991 width=4) (actual time=7820.348..7820.348 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=194334 read=60961 written=7
                     ->  Seq Scan on orders  (cost=0.00..406494.91 rows=15119991 width=4) (actual time=0.010..3896.553 rows=15015000 loops=1)
                           Buffers: shared hit=194334 read=60961 written=7
 Planning time: 2.555 ms
 Execution time: 9057.150 ms
(34 rows)

COMMIT;
COMMIT