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
				('25', '15', '29', '26', '22', '24', '27')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('25', '15', '29', '26', '22', '24', '27')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=698304.22..698304.22 rows=3 width=20) (actual time=15585.187..15585.188 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=280650 read=47969 dirtied=2 written=6713
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52918.87..52918.88 rows=1 width=4) (actual time=727.773..727.773 rows=1 loops=1)
           Buffers: shared hit=24372 read=11968 written=39
           ->  Bitmap Heap Scan on customer  (cost=6648.94..51963.05 rows=382328 width=4) (actual time=141.230..628.499 rows=381136 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,15,29,26,22,24,27}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=24372 read=11968 written=39
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6553.36 rows=382328 width=0) (actual time=129.417..129.417 rows=381136 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{25,15,29,26,22,24,27}'::text[]))
                       Buffers: shared hit=11 read=1052 written=4
   ->  HashAggregate  (cost=645385.27..645385.31 rows=3 width=20) (actual time=15585.114..15585.118 rows=7 loops=1)
         Buffers: shared hit=280648 read=47969 dirtied=2 written=6713
         ->  Hash Anti Join  (cost=601355.57..644942.13 rows=59085 width=20) (actual time=14278.373..15540.952 rows=63314 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=280648 read=47969 dirtied=2 written=6713
               ->  Bitmap Heap Scan on customer  (cost=2910.07..41866.01 rows=140112 width=24) (actual time=827.438..1626.601 rows=190505 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,15,29,26,22,24,27}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=24384 read=47670 written=6710
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.05 rows=140112 width=0) (actual time=815.302..815.302 rows=190505 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{25,15,29,26,22,24,27}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=24382 read=12505 written=41
               ->  Hash  (cost=408509.11..408509.11 rows=15194911 width=4) (actual time=13435.208..13435.208 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=256261 read=299 dirtied=2 written=3
                     ->  Seq Scan on orders  (cost=0.00..408509.11 rows=15194911 width=4) (actual time=0.030..5590.439 rows=15000000 loops=1)
                           Buffers: shared hit=256261 read=299 dirtied=2 written=3
 Total runtime: 15704.433 ms
(30 rows)

COMMIT;
COMMIT