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', '24', '33', '22', '18', '34', '17')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('27', '24', '33', '22', '18', '34', '17')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=698241.89..698241.90 rows=3 width=20) (actual time=10138.827..10138.828 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=55923 read=272712 written=453
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52904.55..52904.56 rows=1 width=4) (actual time=675.758..675.758 rows=1 loops=1)
           Buffers: shared hit=850 read=35492 written=5
           ->  Bitmap Heap Scan on customer customer_1  (cost=6646.77..51949.78 rows=381905 width=4) (actual time=97.765..600.957 rows=381527 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,24,33,22,18,34,17}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=850 read=35492 written=5
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6551.30 rows=381905 width=0) (actual time=88.813..88.813 rows=381527 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{27,24,33,22,18,34,17}'::text[]))
                       Buffers: shared hit=9 read=1055
   ->  HashAggregate  (cost=645337.27..645337.31 rows=3 width=20) (actual time=10138.781..10138.784 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=55920 read=272712 written=453
         ->  Hash Anti Join  (cost=601355.72..644895.18 rows=58945 width=20) (actual time=9579.623..10111.877 rows=63538 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=55920 read=272712 written=453
               ->  Bitmap Heap Scan on customer  (cost=2910.22..41863.74 rows=140020 width=24) (actual time=741.348..1151.107 rows=190473 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,24,33,22,18,34,17}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35182
                     Buffers: shared hit=862 read=71207 written=97
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.21 rows=140020 width=0) (actual time=732.543..732.543 rows=190473 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,24,33,22,18,34,17}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=860 read=36027 written=5
               ->  Hash  (cost=408509.11..408509.11 rows=15194911 width=4) (actual time=8782.520..8782.520 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=55055 read=201505 written=356
                     ->  Seq Scan on orders  (cost=0.00..408509.11 rows=15194911 width=4) (actual time=0.014..4688.563 rows=15000000 loops=1)
                           Buffers: shared hit=55055 read=201505 written=356
 Planning time: 2.543 ms
 Execution time: 10145.932 ms
(34 rows)

COMMIT;
COMMIT