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
				('18', '10', '13', '21', '17', '19', '29')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '10', '13', '21', '17', '19', '29')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694096.30..694096.31 rows=3 width=20) (actual time=9855.155..9855.155 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=291075 read=35782 dirtied=1 written=460
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52892.51..52892.52 rows=1 width=4) (actual time=547.197..547.197 rows=1 loops=1)
           Buffers: shared hit=35288 read=1055 written=59
           ->  Bitmap Heap Scan on customer customer_1  (cost=6644.23..51938.57 rows=381575 width=4) (actual time=97.911..467.121 rows=382408 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,10,13,21,17,19,29}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35288 read=1055 written=59
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6548.83 rows=381575 width=0) (actual time=89.066..89.066 rows=382408 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,10,13,21,17,19,29}'::text[]))
                       Buffers: shared hit=10 read=1055 written=59
   ->  HashAggregate  (cost=641203.71..641203.76 rows=3 width=20) (actual time=9855.095..9855.097 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=291072 read=35782 dirtied=1 written=460
         ->  Hash Anti Join  (cost=597219.63..640763.72 rows=58666 width=20) (actual time=9491.747..9834.184 rows=63774 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=291072 read=35782 dirtied=1 written=460
               ->  Bitmap Heap Scan on customer  (cost=2909.79..41862.32 rows=139982 width=24) (actual time=611.927..843.822 rows=190704 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,10,13,21,17,19,29}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35176
                     Buffers: shared hit=69534 read=2530 written=104
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.79 rows=139982 width=0) (actual time=603.025..603.025 rows=190704 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,10,13,21,17,19,29}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35299 read=1589 written=104
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=8796.544..8796.544 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=221535 read=33252 dirtied=1 written=356
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.021..4585.182 rows=15000000 loops=1)
                           Buffers: shared hit=221535 read=33252 dirtied=1 written=356
 Planning time: 2.663 ms
 Execution time: 9859.733 ms
(34 rows)

COMMIT;
COMMIT