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', '20', '32', '34', '10', '30', '29')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('27', '20', '32', '34', '10', '30', '29')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=697609.81..697609.82 rows=3 width=20) (actual time=12067.561..12067.561 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=204762 read=123611 written=5385
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52873.06..52873.07 rows=1 width=4) (actual time=803.954..803.955 rows=1 loops=1)
           Buffers: shared hit=9 read=36330 written=1663
           ->  Bitmap Heap Scan on customer customer_1  (cost=6640.10..51920.45 rows=381042 width=4) (actual time=83.422..735.212 rows=381480 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,20,32,34,10,30,29}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=9 read=36330 written=1663
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6544.84 rows=381042 width=0) (actual time=75.802..75.802 rows=381480 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{27,20,32,34,10,30,29}'::text[]))
                       Buffers: shared hit=7 read=1055 written=2
   ->  HashAggregate  (cost=644736.67..644736.71 rows=3 width=20) (actual time=12067.506..12067.508 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=204759 read=123611 written=5385
         ->  Hash Anti Join  (cost=600763.57..644296.59 rows=58677 width=20) (actual time=11329.125..12043.283 rows=64047 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=204759 read=123611 written=5385
               ->  Bitmap Heap Scan on customer  (cost=2908.21..41856.70 rows=139828 width=24) (actual time=859.304..1385.728 rows=190756 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,20,32,34,10,30,29}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35175
                     Buffers: shared hit=21 read=72039 written=1691
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2873.25 rows=139828 width=0) (actual time=851.471..851.471 rows=190756 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,20,32,34,10,30,29}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=19 read=36866 written=1691
               ->  Hash  (cost=408106.27..408106.27 rows=15179927 width=4) (actual time=10364.610..10364.610 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=204735 read=51572 written=3694
                     ->  Seq Scan on orders  (cost=0.00..408106.27 rows=15179927 width=4) (actual time=0.032..4527.809 rows=15000000 loops=1)
                           Buffers: shared hit=204735 read=51572 written=3694
 Planning time: 2.767 ms
 Execution time: 12083.285 ms
(34 rows)

COMMIT;
COMMIT