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
				('16', '22', '29', '33', '20', '27', '25')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('16', '22', '29', '33', '20', '27', '25')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694855.89..694855.89 rows=3 width=20) (actual time=9489.581..9489.582 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=247693 read=79410 written=25
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52989.41..52989.42 rows=1 width=4) (actual time=689.693..689.693 rows=1 loops=1)
           Buffers: shared hit=8 read=36334 written=9
           ->  Bitmap Heap Scan on customer customer_1  (cost=6683.69..52030.48 rows=383573 width=4) (actual time=100.866..617.944 rows=381781 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{16,22,29,33,20,27,25}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=8 read=36334 written=9
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6587.79 rows=383573 width=0) (actual time=91.462..91.462 rows=381781 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{16,22,29,33,20,27,25}'::text[]))
                       Buffers: shared hit=6 read=1058
   ->  HashAggregate  (cost=641866.39..641866.44 rows=3 width=20) (actual time=9489.534..9489.536 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=247690 read=79410 written=25
         ->  Hash Anti Join  (cost=597846.79..641422.38 rows=59202 width=20) (actual time=9203.217..9465.756 rows=63737 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=247690 read=79410 written=25
               ->  Bitmap Heap Scan on customer  (cost=2944.46..41914.05 rows=140632 width=24) (actual time=755.794..906.215 rows=190886 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{16,22,29,33,20,27,25}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35165
                     Buffers: shared hit=35182 read=36874 written=9
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2909.30 rows=140632 width=0) (actual time=747.041..747.041 rows=190886 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{16,22,29,33,20,27,25}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=17 read=36874 written=9
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=8374.700..8374.700 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=212505 read=42536 written=16
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.036..3820.486 rows=15015000 loops=1)
                           Buffers: shared hit=212505 read=42536 written=16
 Planning time: 2.880 ms
 Execution time: 9496.731 ms
(34 rows)

COMMIT;
COMMIT