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
				('14', '21', '28', '12', '23', '34', '25')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('14', '21', '28', '12', '23', '34', '25')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694252.68..694252.69 rows=3 width=20) (actual time=18686.486..18686.487 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=319607 read=7498
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52969.64..52969.65 rows=1 width=4) (actual time=1057.663..1057.663 rows=1 loops=1)
           Buffers: shared hit=30551 read=5791
           ->  Bitmap Heap Scan on customer  (cost=6678.63..52011.98 rows=383061 width=4) (actual time=224.251..929.719 rows=381675 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{14,21,28,12,23,34,25}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=30551 read=5791
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6582.87 rows=383061 width=0) (actual time=210.355..210.355 rows=381675 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{14,21,28,12,23,34,25}'::text[]))
                       Buffers: shared hit=7 read=1057
   ->  HashAggregate  (cost=641282.96..641283.01 rows=3 width=20) (actual time=18686.408..18686.411 rows=7 loops=1)
         Buffers: shared hit=319605 read=7498
         ->  Hash Anti Join  (cost=597842.92..640841.76 rows=58827 width=20) (actual time=18070.443..18662.080 rows=63348 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=319605 read=7498
               ->  Bitmap Heap Scan on customer  (cost=2940.59..41902.98 rows=140358 width=24) (actual time=1199.740..1465.998 rows=190722 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{14,21,28,12,23,34,25}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=64671 read=7388
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2905.50 rows=140358 width=0) (actual time=1188.138..1188.138 rows=190722 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{14,21,28,12,23,34,25}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=30561 read=6329
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=16859.357..16859.357 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=254931 read=110
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.018..7656.484 rows=15015000 loops=1)
                           Buffers: shared hit=254931 read=110
 Total runtime: 18789.039 ms
(30 rows)

COMMIT;
COMMIT