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
				('27', '12', '17', '23', '32', '18', '13')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('27', '12', '17', '23', '32', '18', '13')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694647.59..694647.60 rows=3 width=20) (actual time=13348.694..13348.696 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=205323 read=121769 written=75
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52875.96..52875.97 rows=1 width=4) (actual time=1063.295..1063.295 rows=1 loops=1)
           Buffers: shared hit=11 read=36330 written=13
           ->  Bitmap Heap Scan on customer customer_1  (cost=6640.70..51923.15 rows=381122 width=4) (actual time=199.409..979.268 rows=381784 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,12,17,23,32,18,13}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=11 read=36330 written=13
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6545.42 rows=381122 width=0) (actual time=176.232..176.232 rows=381784 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{27,12,17,23,32,18,13}'::text[]))
                       Buffers: shared hit=9 read=1055
   ->  HashAggregate  (cost=641771.56..641771.60 rows=3 width=20) (actual time=13348.616..13348.618 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=205320 read=121769 written=75
         ->  Hash Anti Join  (cost=597809.39..641330.32 rows=58832 width=20) (actual time=12531.336..13323.015 rows=63448 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=205320 read=121769 written=75
               ->  Bitmap Heap Scan on customer  (cost=2907.06..41852.53 rows=139713 width=24) (actual time=1133.864..1765.519 rows=190452 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,12,17,23,32,18,13}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35159
                     Buffers: shared hit=23 read=72022 written=58
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.13 rows=139713 width=0) (actual time=1124.356..1124.356 rows=190452 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{27,12,17,23,32,18,13}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=21 read=36865 written=13
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=11294.661..11294.661 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=205294 read=49747 written=17
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.036..5424.849 rows=15015000 loops=1)
                           Buffers: shared hit=205294 read=49747 written=17
 Planning time: 3.950 ms
 Execution time: 13371.763 ms
(34 rows)

COMMIT;
COMMIT