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
				('13', '33', '22', '31', '12', '20', '16')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('13', '33', '22', '31', '12', '20', '16')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694633.26..694633.27 rows=3 width=20) (actual time=17761.283..17761.283 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=306934 read=20160 written=1337
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52845.03..52845.04 rows=1 width=4) (actual time=732.519..732.520 rows=1 loops=1)
           Buffers: shared hit=35442 read=902
           ->  Bitmap Heap Scan on customer  (cost=6633.26..51894.27 rows=380305 width=4) (actual time=164.347..610.702 rows=382054 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,33,22,31,12,20,16}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35442 read=902
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6538.18 rows=380305 width=0) (actual time=150.412..150.412 rows=382054 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{13,33,22,31,12,20,16}'::text[]))
                       Buffers: shared hit=165 read=902
   ->  HashAggregate  (cost=641788.15..641788.19 rows=3 width=20) (actual time=17761.213..17761.215 rows=7 loops=1)
         Buffers: shared hit=306932 read=20160 written=1337
         ->  Hash Anti Join  (cost=597804.80..641347.36 rows=58772 width=20) (actual time=17020.348..17724.119 rows=63542 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=306932 read=20160 written=1337
               ->  Bitmap Heap Scan on customer  (cost=2902.47..41838.93 rows=139370 width=24) (actual time=832.331..1146.830 rows=191038 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,33,22,31,12,20,16}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70625 read=1423
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2867.63 rows=139370 width=0) (actual time=819.296..819.296 rows=191038 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,33,22,31,12,20,16}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35530 read=1364
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=16178.106..16178.106 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=236304 read=18737 written=1337
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.031..6770.757 rows=15000000 loops=1)
                           Buffers: shared hit=236304 read=18737 written=1337
 Total runtime: 17913.313 ms
(30 rows)

COMMIT;
COMMIT