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
				('34', '20', '31', '17', '28', '16', '18')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('34', '20', '31', '17', '28', '16', '18')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=695314.90..695314.91 rows=3 width=20) (actual time=12954.922..12954.924 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=170068 read=157300 written=133
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52919.31..52919.32 rows=1 width=4) (actual time=887.300..887.300 rows=1 loops=1)
           Buffers: shared hit=11 read=36332 written=29
           ->  Bitmap Heap Scan on customer customer_1  (cost=6649.92..51963.53 rows=382309 width=4) (actual time=106.784..809.193 rows=382371 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,20,31,17,28,16,18}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=11 read=36332 written=29
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6554.34 rows=382309 width=0) (actual time=97.773..97.773 rows=382371 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{34,20,31,17,28,16,18}'::text[]))
                       Buffers: shared hit=9 read=1057
   ->  HashAggregate  (cost=642395.51..642395.56 rows=3 width=20) (actual time=12954.846..12954.847 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=170065 read=157300 written=133
         ->  Hash Anti Join  (cost=598406.31..641952.90 rows=59015 width=20) (actual time=12570.822..12933.788 rows=63697 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=170065 read=157300 written=133
               ->  Bitmap Heap Scan on customer  (cost=2911.51..41868.40 rows=140148 width=24) (actual time=954.976..1184.065 rows=191243 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,20,31,17,28,16,18}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35176
                     Buffers: shared hit=35197 read=36870 written=30
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2876.47 rows=140148 width=0) (actual time=945.817..945.817 rows=191243 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{34,20,31,17,28,16,18}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=21 read=36870 written=30
               ->  Hash  (cost=406494.91..406494.91 rows=15119991 width=4) (actual time=11484.947..11484.947 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=134865 read=120430 written=103
                     ->  Seq Scan on orders  (cost=0.00..406494.91 rows=15119991 width=4) (actual time=0.024..5920.450 rows=15015000 loops=1)
                           Buffers: shared hit=134865 read=120430 written=103
 Planning time: 5.917 ms
 Execution time: 12976.157 ms
(34 rows)

COMMIT;
COMMIT