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
				('27', '15', '21', '32', '22', '30', '33')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('27', '15', '21', '32', '22', '30', '33')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=690704.73..690704.73 rows=3 width=20) (actual time=9933.018..9933.019 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=324018 read=1596
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52966.80..52966.81 rows=1 width=4) (actual time=443.983..443.983 rows=1 loops=1)
           Buffers: shared hit=35286 read=1058
           ->  Bitmap Heap Scan on customer  (cost=6678.04..52009.34 rows=382983 width=4) (actual time=91.238..366.011 rows=382334 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,15,21,32,22,30,33}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35286 read=1058
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6582.29 rows=382983 width=0) (actual time=82.905..82.905 rows=382334 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{27,15,21,32,22,30,33}'::text[]))
                       Buffers: shared hit=8 read=1058
   ->  HashAggregate  (cost=637737.85..637737.89 rows=3 width=20) (actual time=9932.923..9932.924 rows=7 loops=1)
         Buffers: shared hit=324016 read=1596
         ->  Hash Anti Join  (cost=594299.44..637296.73 rows=58816 width=20) (actual time=9548.129..9913.326 rows=63736 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=324016 read=1596
               ->  Bitmap Heap Scan on customer  (cost=2940.30..41901.96 rows=140330 width=24) (actual time=497.600..629.567 rows=190989 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,15,21,32,22,30,33}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70491 read=1596
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2905.22 rows=140330 width=0) (actual time=490.345..490.345 rows=190989 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,15,21,32,22,30,33}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35296 read=1596
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=9036.325..9036.325 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=0.022..4007.700 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Total runtime: 10033.578 ms
(30 rows)

COMMIT;
COMMIT