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
				('24', '18', '32', '29', '23', '22', '26')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('24', '18', '32', '29', '23', '22', '26')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=698188.67..698188.68 rows=3 width=20) (actual time=10934.628..10934.628 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=235979 read=92666 written=108
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52867.47..52867.48 rows=1 width=4) (actual time=538.915..538.916 rows=1 loops=1)
           Buffers: shared hit=30168 read=6174 written=20
           ->  Bitmap Heap Scan on customer customer_1  (cost=6638.91..51915.24 rows=380889 width=4) (actual time=101.731..466.516 rows=381284 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,18,32,29,23,22,26}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=30168 read=6174 written=20
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6543.69 rows=380889 width=0) (actual time=92.413..92.413 rows=381284 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{24,18,32,29,23,22,26}'::text[]))
                       Buffers: shared hit=9 read=1055 written=11
   ->  HashAggregate  (cost=645321.12..645321.17 rows=3 width=20) (actual time=10934.571..10934.572 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=235976 read=92666 written=108
         ->  Hash Anti Join  (cost=601352.70..644881.92 rows=58560 width=20) (actual time=10266.505..10910.385 rows=63418 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=235976 read=92666 written=108
               ->  Bitmap Heap Scan on customer  (cost=2907.21..41853.12 rows=139730 width=24) (actual time=600.398..1106.842 rows=190561 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,18,32,29,23,22,26}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35190
                     Buffers: shared hit=30180 read=41899 written=87
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.27 rows=139730 width=0) (actual time=591.625..591.625 rows=190561 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{24,18,32,29,23,22,26}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=30178 read=6711 written=20
               ->  Hash  (cost=408509.11..408509.11 rows=15194911 width=4) (actual time=9052.880..9052.880 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=205793 read=50767 written=21
                     ->  Seq Scan on orders  (cost=0.00..408509.11 rows=15194911 width=4) (actual time=0.020..4259.378 rows=15015000 loops=1)
                           Buffers: shared hit=205793 read=50767 written=21
 Planning time: 2.931 ms
 Execution time: 10951.204 ms
(34 rows)

COMMIT;
COMMIT