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
				('11', '10', '19', '34', '20', '18', '27')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('11', '10', '19', '34', '20', '18', '27')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695891.06..695891.07 rows=3 width=20) (actual time=10613.365..10613.365 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=103079 read=224529
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52908.69..52908.70 rows=1 width=4) (actual time=676.362..676.362 rows=1 loops=1)
           Buffers: shared hit=13 read=36328
           ->  Bitmap Heap Scan on customer customer_1  (cost=6647.64..51953.64 rows=382019 width=4) (actual time=81.682..610.915 rows=381590 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,10,19,34,20,18,27}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=13 read=36328
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6552.14 rows=382019 width=0) (actual time=73.976..73.976 rows=381590 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{11,10,19,34,20,18,27}'::text[]))
                       Buffers: shared hit=11 read=1052
   ->  HashAggregate  (cost=642982.29..642982.33 rows=3 width=20) (actual time=10613.302..10613.305 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=103076 read=224529
         ->  Hash Anti Join  (cost=598995.52..642541.32 rows=58796 width=20) (actual time=9999.770..10590.449 rows=63686 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=103076 read=224529
               ->  Bitmap Heap Scan on customer  (cost=2910.58..41865.02 rows=140055 width=24) (actual time=733.583..1198.741 rows=190491 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,10,19,34,20,18,27}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35169
                     Buffers: shared hit=25 read=72029
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.56 rows=140055 width=0) (actual time=724.963..724.963 rows=190491 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,10,19,34,20,18,27}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=23 read=36862
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=9040.355..9040.355 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=103048 read=152500
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.026..4750.165 rows=15000000 loops=1)
                           Buffers: shared hit=103048 read=152500
 Planning time: 2.648 ms
 Execution time: 10628.881 ms
(34 rows)

COMMIT;
COMMIT