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
				('18', '22', '32', '31', '13', '20', '10')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '22', '32', '31', '13', '20', '10')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=697787.60..697787.61 rows=3 width=20) (actual time=11540.194..11540.195 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=327363 read=1011 written=65
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52969.80..52969.81 rows=1 width=4) (actual time=494.199..494.199 rows=1 loops=1)
           Buffers: shared hit=35738 read=603 written=48
           ->  Bitmap Heap Scan on customer customer_1  (cost=6679.51..52012.21 rows=383036 width=4) (actual time=84.788..419.395 rows=381770 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,22,32,31,13,20,10}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=35738 read=603 written=48
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6583.75 rows=383036 width=0) (actual time=76.685..76.685 rows=381770 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,22,32,31,13,20,10}'::text[]))
                       Buffers: shared hit=462 read=602 written=48
   ->  HashAggregate  (cost=644817.72..644817.77 rows=3 width=20) (actual time=11540.129..11540.131 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=327360 read=1011 written=65
         ->  Hash Anti Join  (cost=600799.10..644375.34 rows=58984 width=20) (actual time=11079.269..11518.859 rows=63682 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=327360 read=1011 written=65
               ->  Bitmap Heap Scan on customer  (cost=2943.74..41911.44 rows=140560 width=24) (actual time=549.618..795.380 rows=190758 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,22,32,31,13,20,10}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35173
                     Buffers: shared hit=71050 read=1011 written=65
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2908.60 rows=140560 width=0) (actual time=541.461..541.461 rows=190758 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,22,32,31,13,20,10}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35978 read=910 written=65
               ->  Hash  (cost=408106.27..408106.27 rows=15179927 width=4) (actual time=10336.991..10336.991 rows=15000000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658416kB
                     Buffers: shared hit=256307
                     ->  Seq Scan on orders  (cost=0.00..408106.27 rows=15179927 width=4) (actual time=0.019..4355.245 rows=15000000 loops=1)
                           Buffers: shared hit=256307
 Planning time: 2.507 ms
 Execution time: 11556.463 ms
(34 rows)

COMMIT;
COMMIT