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
				('11', '16', '25', '30', '22', '21', '26')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('11', '16', '25', '30', '22', '21', '26')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691165.14..691165.15 rows=3 width=20) (actual time=8317.187..8317.187 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=323993 read=1596
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52891.53..52891.54 rows=1 width=4) (actual time=416.340..416.341 rows=1 loops=1)
           Buffers: shared hit=35286 read=1056
           ->  Bitmap Heap Scan on customer  (cost=6643.13..51937.58 rows=381579 width=4) (actual time=89.435..338.508 rows=381423 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,16,25,30,22,21,26}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35286 read=1056
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6547.74 rows=381579 width=0) (actual time=81.165..81.165 rows=381423 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{11,16,25,30,22,21,26}'::text[]))
                       Buffers: shared hit=8 read=1056
   ->  HashAggregate  (cost=638273.53..638273.58 rows=3 width=20) (actual time=8317.105..8317.107 rows=7 loops=1)
         Buffers: shared hit=323991 read=1596
         ->  Hash Anti Join  (cost=594266.92..637827.29 rows=59499 width=20) (actual time=8016.368..8297.690 rows=63505 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323991 read=1596
               ->  Bitmap Heap Scan on customer  (cost=2907.78..41857.84 rows=139888 width=24) (actual time=469.344..602.258 rows=190877 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,16,25,30,22,21,26}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70466 read=1596
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.81 rows=139888 width=0) (actual time=462.114..462.114 rows=190877 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,16,25,30,22,21,26}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35295 read=1596
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=7540.743..7540.743 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=253522
                     ->  Seq Scan on orders  (cost=0.00..403671.84 rows=15014984 width=4) (actual time=0.055..3991.710 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Total runtime: 8344.249 ms
(30 rows)

COMMIT;
COMMIT