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
				('12', '21', '26', '30', '23', '33', '16')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('12', '21', '26', '30', '23', '33', '16')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=699494.27..699494.28 rows=3 width=20) (actual time=22220.253..22220.254 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=267106 read=61783 dirtied=253 written=1497
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52967.17..52967.18 rows=1 width=4) (actual time=1270.134..1270.134 rows=1 loops=1)
           Buffers: shared hit=23890 read=12455 written=1168
           ->  Bitmap Heap Scan on customer  (cost=6678.09..52009.68 rows=382994 width=4) (actual time=199.907..1141.960 rows=382126 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,21,26,30,23,33,16}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=23890 read=12455 written=1168
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6582.34 rows=382994 width=0) (actual time=182.024..182.024 rows=382126 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{12,21,26,30,23,33,16}'::text[]))
                       Buffers: shared hit=6 read=1061 written=100
   ->  HashAggregate  (cost=646527.02..646527.07 rows=3 width=20) (actual time=22220.189..22220.191 rows=7 loops=1)
         Buffers: shared hit=267104 read=61783 dirtied=253 written=1497
         ->  Hash Anti Join  (cost=601976.65..646081.54 rows=59398 width=20) (actual time=20241.117..22148.201 rows=63597 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=267104 read=61783 dirtied=253 written=1497
               ->  Bitmap Heap Scan on customer  (cost=2941.02..41904.46 rows=140398 width=24) (actual time=1399.992..2815.149 rows=191149 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,21,26,30,23,33,16}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=23901 read=48170 written=1206
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2905.92 rows=140398 width=0) (actual time=1388.395..1388.395 rows=191149 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,21,26,30,23,33,16}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=23899 read=12996 written=1206
               ->  Hash  (cost=408911.95..408911.95 rows=15209895 width=4) (actual time=18833.030..18833.030 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=243200 read=13613 dirtied=253 written=291
                     ->  Seq Scan on orders  (cost=0.00..408911.95 rows=15209895 width=4) (actual time=0.016..9592.960 rows=15015000 loops=1)
                           Buffers: shared hit=243200 read=13613 dirtied=253 written=291
 Total runtime: 22370.401 ms
(30 rows)

COMMIT;
COMMIT