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
				('21', '34', '11', '23', '28', '29', '19')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('21', '34', '11', '23', '28', '29', '19')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694163.71..694163.72 rows=3 width=20) (actual time=21105.781..21105.782 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=276974 read=50135
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52923.70..52923.71 rows=1 width=4) (actual time=1136.661..1136.661 rows=1 loops=1)
           Buffers: shared hit=35291 read=1052
           ->  Bitmap Heap Scan on customer  (cost=6649.97..51967.54 rows=382460 width=4) (actual time=270.596..1000.908 rows=381922 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,34,11,23,28,29,19}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35291 read=1052
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6554.35 rows=382460 width=0) (actual time=258.087..258.087 rows=381922 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{21,34,11,23,28,29,19}'::text[]))
                       Buffers: shared hit=13 read=1052
   ->  HashAggregate  (cost=641239.94..641239.98 rows=3 width=20) (actual time=21105.706..21105.708 rows=7 loops=1)
         Buffers: shared hit=276972 read=50135
         ->  Hash Anti Join  (cost=597812.69..640799.43 rows=58735 width=20) (actual time=19964.108..21051.144 rows=63488 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=276972 read=50135
               ->  Bitmap Heap Scan on customer  (cost=2910.36..41866.98 rows=140138 width=24) (actual time=1251.024..1879.635 rows=190692 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,34,11,23,28,29,19}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=67910 read=4153
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.33 rows=140138 width=0) (actual time=1237.183..1237.183 rows=190692 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,34,11,23,28,29,19}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35303 read=1587
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=18700.097..18700.097 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=209059 read=45982
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.027..9264.133 rows=15015000 loops=1)
                           Buffers: shared hit=209059 read=45982
 Total runtime: 21241.137 ms
(30 rows)

COMMIT;
COMMIT