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
				('11', '13', '31', '21', '32', '18', '17')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('11', '13', '31', '21', '32', '18', '17')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693089.52..693089.53 rows=3 width=20) (actual time=23699.843..23699.844 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=324466 read=1612
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=53018.98..53018.99 rows=1 width=4) (actual time=833.448..833.448 rows=1 loops=1)
           Buffers: shared hit=35271 read=1072
           ->  Bitmap Heap Scan on customer  (cost=6689.10..52057.95 rows=384413 width=4) (actual time=154.230..720.013 rows=382175 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,13,31,21,32,18,17}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35271 read=1072
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6593.00 rows=384413 width=0) (actual time=141.619..141.619 rows=382175 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{11,13,31,21,32,18,17}'::text[]))
                       Buffers: shared hit=9 read=1056
   ->  HashAggregate  (cost=640070.46..640070.50 rows=3 width=20) (actual time=23699.763..23699.768 rows=7 loops=1)
         Buffers: shared hit=324464 read=1612
         ->  Hash Anti Join  (cost=595485.75..639623.32 rows=59618 width=20) (actual time=22494.041..23640.399 rows=63596 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=324464 read=1612
               ->  Bitmap Heap Scan on customer  (cost=2946.33..41923.42 rows=140918 width=24) (actual time=1079.746..1686.382 rows=190704 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,13,31,21,32,18,17}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70433 read=1612
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2911.10 rows=140918 width=0) (actual time=1040.117..1040.117 rows=190704 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{11,13,31,21,32,18,17}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35281 read=1609
               ->  Hash  (cost=404477.52..404477.52 rows=15044952 width=4) (actual time=21381.537..21381.537 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=254028
                     ->  Seq Scan on orders  (cost=0.00..404477.52 rows=15044952 width=4) (actual time=0.037..8421.467 rows=15015000 loops=1)
                           Buffers: shared hit=254028
 Total runtime: 23867.000 ms
(30 rows)

COMMIT;
COMMIT