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', '25', '23', '27', '10', '30', '32')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('15', '25', '23', '27', '10', '30', '32')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694145.00..694145.01 rows=3 width=20) (actual time=11061.363..11061.364 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=315727 read=11100 written=4
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52920.67..52920.68 rows=1 width=4) (actual time=489.428..489.428 rows=1 loops=1)
           Buffers: shared hit=35215 read=1125
           ->  Bitmap Heap Scan on customer customer_1  (cost=6650.19..51964.80 rows=382347 width=4) (actual time=97.170..411.524 rows=381643 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,25,23,27,10,30,32}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35215 read=1125
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6554.61 rows=382347 width=0) (actual time=87.983..87.983 rows=381643 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{15,25,23,27,10,30,32}'::text[]))
                       Buffers: shared hit=46 read=1016
   ->  HashAggregate  (cost=641224.25..641224.29 rows=3 width=20) (actual time=11061.290..11061.293 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=315724 read=11100 written=4
         ->  Hash Anti Join  (cost=597222.57..640783.36 rows=58785 width=20) (actual time=10631.013..11039.777 rows=63628 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=315724 read=11100 written=4
               ->  Bitmap Heap Scan on customer  (cost=2912.73..41872.69 rows=140265 width=24) (actual time=560.956..812.063 rows=190682 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,25,23,27,10,30,32}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35148
                     Buffers: shared hit=70264 read=1770
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2877.66 rows=140265 width=0) (actual time=551.572..551.572 rows=190682 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,25,23,27,10,30,32}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35225 read=1661
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=9967.568..9967.568 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=245457 read=9330 written=4
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.021..4799.605 rows=15015000 loops=1)
                           Buffers: shared hit=245457 read=9330 written=4
 Planning time: 3.574 ms
 Execution time: 11073.507 ms
(34 rows)

COMMIT;
COMMIT