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
				('20', '10', '27', '22', '15', '18', '12')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('20', '10', '27', '22', '15', '18', '12')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694067.59..694067.60 rows=3 width=20) (actual time=19270.380..19270.381 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=254888 read=71962 dirtied=22 written=23
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52857.27..52857.28 rows=1 width=4) (actual time=1229.637..1229.637 rows=1 loops=1)
           Buffers: shared hit=8 read=36335 written=18
           ->  Bitmap Heap Scan on customer  (cost=6635.86..51905.66 rows=380640 width=4) (actual time=160.116..1110.233 rows=381759 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,10,27,22,15,18,12}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=8 read=36335 written=18
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6540.70 rows=380640 width=0) (actual time=147.025..147.025 rows=381759 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{20,10,27,22,15,18,12}'::text[]))
                       Buffers: shared hit=6 read=1059
   ->  HashAggregate  (cost=641210.25..641210.29 rows=3 width=20) (actual time=19270.292..19270.295 rows=7 loops=1)
         Buffers: shared hit=254886 read=71962 dirtied=22 written=23
         ->  Hash Anti Join  (cost=597215.39..640765.39 rows=59315 width=20) (actual time=18335.846..19214.485 rows=63532 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=254886 read=71962 dirtied=22 written=23
               ->  Bitmap Heap Scan on customer  (cost=2905.55..41849.97 rows=139673 width=24) (actual time=1340.939..1765.457 rows=190690 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,10,27,22,15,18,12}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=31236 read=40822 written=23
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2870.64 rows=139673 width=0) (actual time=1327.621..1327.621 rows=190690 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{20,10,27,22,15,18,12}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=17 read=36872 written=23
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=16982.034..16982.034 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=223647 read=31140 dirtied=22
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.063..7668.260 rows=15015000 loops=1)
                           Buffers: shared hit=223647 read=31140 dirtied=22
 Total runtime: 19462.281 ms
(30 rows)

COMMIT;
COMMIT