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
				('26', '23', '31', '14', '32', '10', '15')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('26', '23', '31', '14', '32', '10', '15')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691758.80..691758.81 rows=3 width=20) (actual time=11630.760..11630.761 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=324357 read=1482
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52913.18..52913.19 rows=1 width=4) (actual time=728.270..728.270 rows=1 loops=1)
           Buffers: shared hit=35745 read=597
           ->  Bitmap Heap Scan on customer customer_1  (cost=6648.62..51957.82 rows=382141 width=4) (actual time=137.579..584.499 rows=381919 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,23,31,14,32,10,15}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35745 read=597
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6553.08 rows=382141 width=0) (actual time=125.365..125.365 rows=381919 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{26,23,31,14,32,10,15}'::text[]))
                       Buffers: shared hit=467 read=597
   ->  HashAggregate  (cost=638845.55..638845.59 rows=3 width=20) (actual time=11630.678..11630.679 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=324354 read=1482
         ->  Hash Anti Join  (cost=594860.15..638403.12 rows=58990 width=20) (actual time=11252.809..11610.452 rows=63256 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=324354 read=1482
               ->  Bitmap Heap Scan on customer  (cost=2910.87..41866.15 rows=140087 width=24) (actual time=825.100..1050.955 rows=190932 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,23,31,14,32,10,15}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35169
                     Buffers: shared hit=71156 read=902
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2875.84 rows=140087 width=0) (actual time=812.738..812.738 rows=190932 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{26,23,31,14,32,10,15}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35987 read=902
               ->  Hash  (cost=404074.68..404074.68 rows=15029968 width=4) (actual time=10298.228..10298.228 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=253195 read=580
                     ->  Seq Scan on orders  (cost=0.00..404074.68 rows=15029968 width=4) (actual time=0.022..4601.329 rows=15015000 loops=1)
                           Buffers: shared hit=253195 read=580
 Planning time: 3.741 ms
 Execution time: 11636.043 ms
(34 rows)

COMMIT;
COMMIT