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
				('33', '12', '13', '31', '17', '21', '20')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('33', '12', '13', '31', '17', '21', '20')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=692356.07..692356.08 rows=3 width=20) (actual time=13768.561..13768.562 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=190082 read=136003 dirtied=252 written=33
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52917.32..52917.33 rows=1 width=4) (actual time=1198.262..1198.263 rows=1 loops=1)
           Buffers: shared hit=12 read=36331
           ->  Bitmap Heap Scan on customer customer_1  (cost=6649.49..51961.68 rows=382255 width=4) (actual time=148.605..1071.975 rows=382403 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,12,13,31,17,21,20}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=12 read=36331
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6553.92 rows=382255 width=0) (actual time=131.466..131.466 rows=382403 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{33,12,13,31,17,21,20}'::text[]))
                       Buffers: shared hit=10 read=1055
   ->  HashAggregate  (cost=639438.67..639438.72 rows=3 width=20) (actual time=13768.477..13768.480 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=190079 read=136003 dirtied=252 written=33
         ->  Hash Anti Join  (cost=595450.72..638996.12 rows=59007 width=20) (actual time=12902.204..13742.283 rows=63741 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=190079 read=136003 dirtied=252 written=33
               ->  Bitmap Heap Scan on customer  (cost=2911.30..41867.66 rows=140128 width=24) (actual time=1302.995..1932.706 rows=191027 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,12,13,31,17,21,20}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35160
                     Buffers: shared hit=24 read=72027 written=19
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2876.26 rows=140128 width=0) (actual time=1290.312..1290.312 rows=191027 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{33,12,13,31,17,21,20}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=22 read=36869
               ->  Hash  (cost=404477.52..404477.52 rows=15044952 width=4) (actual time=11541.491..11541.491 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=190052 read=63976 dirtied=252 written=14
                     ->  Seq Scan on orders  (cost=0.00..404477.52 rows=15044952 width=4) (actual time=0.035..5945.182 rows=15015000 loops=1)
                           Buffers: shared hit=190052 read=63976 dirtied=252 written=14
 Planning time: 4.549 ms
 Execution time: 13776.509 ms
(34 rows)

COMMIT;
COMMIT