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', '23', '29', '18', '21', '20', '27')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('22', '23', '29', '18', '21', '20', '27')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695353.70..695353.71 rows=3 width=20) (actual time=19056.733..19056.733 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=290107 read=36999 written=187
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52963.03..52963.04 rows=1 width=4) (actual time=1581.208..1581.209 rows=1 loops=1)
           Buffers: shared hit=14 read=36329 written=187
           ->  Bitmap Heap Scan on customer  (cost=6677.22..52005.82 rows=382880 width=4) (actual time=159.261..1475.686 rows=381628 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{22,23,29,18,21,20,27}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=14 read=36329 written=187
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6581.50 rows=382880 width=0) (actual time=146.597..146.597 rows=381628 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{22,23,29,18,21,20,27}'::text[]))
                       Buffers: shared hit=12 read=1053 written=15
   ->  HashAggregate  (cost=642390.59..642390.64 rows=3 width=20) (actual time=19056.649..19056.653 rows=7 loops=1)
         Buffers: shared hit=290105 read=36999 written=187
         ->  Hash Anti Join  (cost=597842.92..641945.24 rows=59380 width=20) (actual time=18301.651..19020.099 rows=63672 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=290105 read=36999 written=187
               ->  Bitmap Heap Scan on customer  (cost=2940.59..41902.96 rows=140357 width=24) (actual time=1651.400..2065.456 rows=190647 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{22,23,29,18,21,20,27}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35195 read=36865 written=187
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2905.50 rows=140357 width=0) (actual time=1642.816..1642.816 rows=190647 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{22,23,29,18,21,20,27}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=26 read=36864 written=187
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=16642.526..16642.526 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=254907 read=134
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.027..7992.545 rows=15015000 loops=1)
                           Buffers: shared hit=254907 read=134
 Total runtime: 19172.614 ms
(30 rows)

COMMIT;
COMMIT