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
				('19', '14', '32', '18', '16', '20', '31')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('19', '14', '32', '18', '16', '20', '31')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691152.99..691153.00 rows=3 width=20) (actual time=9201.360..9201.360 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=323991 read=1596
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52881.42..52881.43 rows=1 width=4) (actual time=483.240..483.240 rows=1 loops=1)
           Buffers: shared hit=35289 read=1057
           ->  Bitmap Heap Scan on customer  (cost=6641.02..51928.17 rows=381301 width=4) (actual time=98.395..405.748 rows=382551 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,14,32,18,16,20,31}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35289 read=1057
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6545.69 rows=381301 width=0) (actual time=90.007..90.007 rows=382551 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{19,14,32,18,16,20,31}'::text[]))
                       Buffers: shared hit=11 read=1057
   ->  HashAggregate  (cost=638271.49..638271.53 rows=3 width=20) (actual time=9201.240..9201.242 rows=7 loops=1)
         Buffers: shared hit=323989 read=1596
         ->  Hash Anti Join  (cost=594265.34..637829.54 rows=58926 width=20) (actual time=8832.079..9181.720 rows=63669 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323989 read=1596
               ->  Bitmap Heap Scan on customer  (cost=2906.20..41852.24 rows=139735 width=24) (actual time=536.516..682.243 rows=191102 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,14,32,18,16,20,31}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70464 read=1596
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2871.27 rows=139735 width=0) (actual time=529.151..529.151 rows=191102 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,14,32,18,16,20,31}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35298 read=1596
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=8285.136..8285.136 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=0.026..4483.977 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Total runtime: 9237.396 ms
(30 rows)

COMMIT;
COMMIT