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', '16', '29', '23', '17', '28', '30')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('13', '16', '29', '23', '17', '28', '30')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=697054.40..697054.41 rows=3 width=20) (actual time=13877.597..13877.597 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=259154 read=68959
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52872.00..52872.01 rows=1 width=4) (actual time=598.223..598.224 rows=1 loops=1)
           Buffers: shared hit=27926 read=8418
           ->  Bitmap Heap Scan on customer  (cost=6639.01..51919.39 rows=381043 width=4) (actual time=97.411..510.682 rows=381922 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,16,29,23,17,28,30}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=27926 read=8418
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6543.75 rows=381043 width=0) (actual time=88.078..88.078 rows=381922 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{13,16,29,23,17,28,30}'::text[]))
                       Buffers: shared hit=11 read=1055
   ->  HashAggregate  (cost=644182.33..644182.37 rows=3 width=20) (actual time=13877.531..13877.533 rows=7 loops=1)
         Buffers: shared hit=259152 read=68959
         ->  Hash Anti Join  (cost=600172.64..643738.43 rows=59186 width=20) (actual time=12901.657..13848.198 rows=63685 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=259152 read=68959
               ->  Bitmap Heap Scan on customer  (cost=2907.42..41856.53 rows=139852 width=24) (actual time=676.141..1243.596 rows=190892 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,16,29,23,17,28,30}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=27939 read=44115
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.46 rows=139852 width=0) (actual time=665.281..665.281 rows=190892 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,16,29,23,17,28,30}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=27936 read=8955
               ->  Hash  (cost=407703.43..407703.43 rows=15164943 width=4) (actual time=12208.753..12208.753 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=231210 read=24844
                     ->  Seq Scan on orders  (cost=0.00..407703.43 rows=15164943 width=4) (actual time=0.022..5466.337 rows=15000000 loops=1)
                           Buffers: shared hit=231210 read=24844
 Total runtime: 14027.358 ms
(30 rows)

COMMIT;
COMMIT