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
				('28', '12', '32', '26', '29', '25', '30')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('28', '12', '32', '26', '29', '25', '30')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=697641.94..697641.95 rows=3 width=20) (actual time=10104.511..10104.511 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=286553 read=41836 dirtied=62 written=75
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52904.41..52904.42 rows=1 width=4) (actual time=760.113..760.113 rows=1 loops=1)
           Buffers: shared hit=12 read=36329
           ->  Bitmap Heap Scan on customer customer_1  (cost=6646.72..51949.65 rows=381902 width=4) (actual time=90.382..690.023 rows=381536 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,12,32,26,29,25,30}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=12 read=36329
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6551.25 rows=381902 width=0) (actual time=81.606..81.606 rows=381536 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{28,12,32,26,29,25,30}'::text[]))
                       Buffers: shared hit=10 read=1053
   ->  HashAggregate  (cost=644737.45..644737.50 rows=3 width=20) (actual time=10104.442..10104.443 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=286550 read=41836 dirtied=62 written=75
         ->  Hash Anti Join  (cost=600765.72..644290.93 rows=59536 width=20) (actual time=9751.454..10082.891 rows=63836 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=286550 read=41836 dirtied=62 written=75
               ->  Bitmap Heap Scan on customer  (cost=2910.36..41864.33 rows=140037 width=24) (actual time=818.924..1028.448 rows=190871 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,12,32,26,29,25,30}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35187
                     Buffers: shared hit=35206 read=36870 written=1
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.35 rows=140037 width=0) (actual time=810.831..810.831 rows=190871 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,12,32,26,29,25,30}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=22 read=36867
               ->  Hash  (cost=408106.27..408106.27 rows=15179927 width=4) (actual time=8800.336..8800.336 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=251341 read=4966 dirtied=62 written=74
                     ->  Seq Scan on orders  (cost=0.00..408106.27 rows=15179927 width=4) (actual time=0.022..4127.081 rows=15015000 loops=1)
                           Buffers: shared hit=251341 read=4966 dirtied=62 written=74
 Planning time: 3.117 ms
 Execution time: 10117.652 ms
(34 rows)

COMMIT;
COMMIT