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
				('30', '22', '31', '33', '34', '25', '19')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('30', '22', '31', '33', '34', '25', '19')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=696117.10..696117.10 rows=3 width=20) (actual time=18181.153..18181.155 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=290384 read=37224 dirtied=252 written=25
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=53009.75..53009.76 rows=1 width=4) (actual time=813.036..813.036 rows=1 loops=1)
           Buffers: shared hit=35287 read=1057
           ->  Bitmap Heap Scan on customer  (cost=6687.15..52049.35 rows=384160 width=4) (actual time=155.861..670.306 rows=381855 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,22,31,33,34,25,19}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35287 read=1057
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6591.11 rows=384160 width=0) (actual time=143.674..143.674 rows=381855 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{30,22,31,33,34,25,19}'::text[]))
                       Buffers: shared hit=9 read=1057
   ->  HashAggregate  (cost=643107.26..643107.31 rows=3 width=20) (actual time=18181.069..18181.073 rows=7 loops=1)
         Buffers: shared hit=290382 read=37224 dirtied=252 written=25
         ->  Hash Anti Join  (cost=599031.76..642658.29 rows=59863 width=20) (actual time=16622.155..18114.381 rows=63865 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=290382 read=37224 dirtied=252 written=25
               ->  Bitmap Heap Scan on customer  (cost=2946.83..41925.16 rows=140965 width=24) (actual time=954.871..1981.797 rows=190916 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,22,31,33,34,25,19}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35298 read=36757 written=23
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2911.59 rows=140965 width=0) (actual time=935.564..935.564 rows=190916 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{30,22,31,33,34,25,19}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35296 read=1596
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=15650.830..15650.830 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=255081 read=467 dirtied=252 written=2
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.031..7310.442 rows=15015000 loops=1)
                           Buffers: shared hit=255081 read=467 dirtied=252 written=2
 Total runtime: 18371.417 ms
(30 rows)

COMMIT;
COMMIT