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
				('15', '21', '27', '26', '34', '19', '14')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('15', '21', '27', '26', '34', '19', '14')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695824.50..695824.51 rows=3 width=20) (actual time=12114.487..12114.488 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=216737 read=110886 written=1651
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52872.67..52872.68 rows=1 width=4) (actual time=927.718..927.719 rows=1 loops=1)
           Buffers: shared hit=667 read=35676 written=47
           ->  Bitmap Heap Scan on customer customer_1  (cost=6639.99..51920.08 rows=381032 width=4) (actual time=115.845..842.872 rows=382268 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,21,27,26,34,19,14}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=667 read=35676 written=47
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6544.74 rows=381032 width=0) (actual time=105.115..105.115 rows=382268 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{15,21,27,26,34,19,14}'::text[]))
                       Buffers: shared hit=10 read=1055 written=1
   ->  HashAggregate  (cost=642951.76..642951.80 rows=3 width=20) (actual time=12114.417..12114.419 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=216734 read=110886 written=1651
         ->  Hash Anti Join  (cost=598991.64..642510.62 rows=58818 width=20) (actual time=11699.224..12092.712 rows=63299 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=216734 read=110886 written=1651
               ->  Bitmap Heap Scan on customer  (cost=2906.70..41851.30 rows=139680 width=24) (actual time=993.622..1257.439 rows=190906 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,21,27,26,34,19,14}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35181
                     Buffers: shared hit=32846 read=39223 written=52
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2871.78 rows=139680 width=0) (actual time=984.397..984.397 rows=190906 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,21,27,26,34,19,14}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=676 read=36212 written=47
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=10501.549..10501.549 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=183885 read=71663 written=1599
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.028..5365.213 rows=15000000 loops=1)
                           Buffers: shared hit=183885 read=71663 written=1599
 Planning time: 4.562 ms
 Execution time: 12130.036 ms
(34 rows)

COMMIT;
COMMIT