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
				('28', '10', '17', '27', '15', '21', '22')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('28', '10', '17', '27', '15', '21', '22')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694640.00..694640.01 rows=3 width=20) (actual time=33563.098..33563.099 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=137578 read=189259 dirtied=505 written=19
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52899.88..52899.89 rows=1 width=4) (actual time=3392.050..3392.051 rows=1 loops=1)
           Buffers: shared hit=82 read=36260
           ->  Bitmap Heap Scan on customer  (cost=6644.92..51945.36 rows=381807 width=4) (actual time=283.011..3259.313 rows=382001 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,10,17,27,15,21,22}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=82 read=36260
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6549.47 rows=381807 width=0) (actual time=270.403..270.403 rows=382001 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{28,10,17,27,15,21,22}'::text[]))
                       Buffers: shared hit=8 read=1056
   ->  HashAggregate  (cost=641740.05..641740.09 rows=3 width=20) (actual time=33562.992..33563.000 rows=7 loops=1)
         Buffers: shared hit=137576 read=189259 dirtied=505 written=19
         ->  Hash Anti Join  (cost=597218.41..641295.94 rows=59214 width=20) (actual time=32432.031..33508.126 rows=63324 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=137576 read=189259 dirtied=505 written=19
               ->  Bitmap Heap Scan on customer  (cost=2908.57..41860.60 rows=139963 width=24) (actual time=3507.946..4087.269 rows=190796 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,10,17,27,15,21,22}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35168 read=36877
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2873.58 rows=139963 width=0) (actual time=3494.047..3494.047 rows=190796 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,10,17,27,15,21,22}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=92 read=36796
               ->  Hash  (cost=405686.04..405686.04 rows=15089904 width=4) (actual time=28906.251..28906.251 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=102405 read=152382 dirtied=505 written=19
                     ->  Seq Scan on orders  (cost=0.00..405686.04 rows=15089904 width=4) (actual time=0.034..17099.571 rows=15015000 loops=1)
                           Buffers: shared hit=102405 read=152382 dirtied=505 written=19
 Total runtime: 33735.137 ms
(30 rows)

COMMIT;
COMMIT