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
				('33', '12', '18', '32', '30', '15', '20')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('33', '12', '18', '32', '30', '15', '20')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=696686.87..696686.88 rows=3 width=20) (actual time=12052.455..12052.456 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=221759 read=106115 written=174
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=53016.81..53016.82 rows=1 width=4) (actual time=545.918..545.919 rows=1 loops=1)
           Buffers: shared hit=33959 read=2386 written=7
           ->  Bitmap Heap Scan on customer customer_1  (cost=6689.49..52056.00 rows=384324 width=4) (actual time=101.720..468.617 rows=382741 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,12,18,32,30,15,20}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=33959 read=2386 written=7
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6593.41 rows=384324 width=0) (actual time=92.356..92.356 rows=382741 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{33,12,18,32,30,15,20}'::text[]))
                       Buffers: shared hit=7 read=1060 written=2
   ->  HashAggregate  (cost=643669.98..643670.03 rows=3 width=20) (actual time=12052.398..12052.400 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=221756 read=106115 written=174
         ->  Hash Anti Join  (cost=599623.20..643226.82 rows=59088 width=20) (actual time=11577.001..12030.244 rows=64087 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=221756 read=106115 written=174
               ->  Bitmap Heap Scan on customer  (cost=2948.12..41927.11 rows=140990 width=24) (actual time=612.483..922.059 rows=191222 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,12,18,32,30,15,20}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35173
                     Buffers: shared hit=58651 read=13416 written=19
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2912.87 rows=140990 width=0) (actual time=603.621..603.621 rows=191222 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,12,18,32,30,15,20}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=33969 read=2925 written=9
               ->  Hash  (cost=407300.59..407300.59 rows=15149959 width=4) (actual time=10865.008..10865.008 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=163102 read=92699 written=155
                     ->  Seq Scan on orders  (cost=0.00..407300.59 rows=15149959 width=4) (actual time=0.024..5228.747 rows=15015000 loops=1)
                           Buffers: shared hit=163102 read=92699 written=155
 Planning time: 2.862 ms
 Execution time: 12074.489 ms
(34 rows)

COMMIT;
COMMIT