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', '29', '18', '28', '15', '10', '23')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('12', '29', '18', '28', '15', '10', '23')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695851.51..695851.51 rows=3 width=20) (actual time=10844.076..10844.077 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=224775 read=102846 written=71
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52892.82..52892.83 rows=1 width=4) (actual time=839.686..839.686 rows=1 loops=1)
           Buffers: shared hit=11 read=36331 written=60
           ->  Bitmap Heap Scan on customer customer_1  (cost=6644.28..51938.86 rows=381584 width=4) (actual time=93.545..770.964 rows=382080 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,29,18,28,15,10,23}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=11 read=36331 written=60
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6548.88 rows=381584 width=0) (actual time=84.874..84.874 rows=382080 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{12,29,18,28,15,10,23}'::text[]))
                       Buffers: shared hit=8 read=1057
   ->  HashAggregate  (cost=642958.61..642958.65 rows=3 width=20) (actual time=10844.008..10844.008 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=224772 read=102846 written=71
         ->  Hash Anti Join  (cost=598994.15..642512.45 rows=59487 width=20) (actual time=10471.172..10823.256 rows=63547 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=224772 read=102846 written=71
               ->  Bitmap Heap Scan on customer  (cost=2909.21..41860.11 rows=139920 width=24) (actual time=899.620..1128.161 rows=190766 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,29,18,28,15,10,23}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35178
                     Buffers: shared hit=35196 read=36871 written=60
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2874.23 rows=139920 width=0) (actual time=891.093..891.093 rows=190766 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{12,29,18,28,15,10,23}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=20 read=36869 written=60
               ->  Hash  (cost=406897.75..406897.75 rows=15134975 width=4) (actual time=9462.522..9462.522 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=189573 read=65975 written=11
                     ->  Seq Scan on orders  (cost=0.00..406897.75 rows=15134975 width=4) (actual time=0.019..4857.399 rows=15015000 loops=1)
                           Buffers: shared hit=189573 read=65975 written=11
 Planning time: 2.855 ms
 Execution time: 10871.726 ms
(34 rows)

COMMIT;
COMMIT