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
				('23', '21', '32', '26', '10', '24', '18')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('23', '21', '32', '26', '10', '24', '18')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=694702.59..694702.60 rows=3 width=20) (actual time=25452.758..25452.759 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=285699 read=41423 dirtied=254 written=5765
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52888.21..52888.22 rows=1 width=4) (actual time=4095.963..4095.963 rows=1 loops=1)
           Buffers: shared hit=9 read=36333 written=5618
           ->  Bitmap Heap Scan on customer  (cost=6642.43..51934.49 rows=381488 width=4) (actual time=294.134..3962.642 rows=381595 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{23,21,32,26,10,24,18}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=9 read=36333 written=5618
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6547.06 rows=381488 width=0) (actual time=282.643..282.643 rows=381595 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{23,21,32,26,10,24,18}'::text[]))
                       Buffers: shared hit=7 read=1057 written=86
   ->  HashAggregate  (cost=641814.31..641814.35 rows=3 width=20) (actual time=25452.672..25452.675 rows=7 loops=1)
         Buffers: shared hit=285697 read=41423 dirtied=254 written=5765
         ->  Hash Anti Join  (cost=597809.75..641368.17 rows=59485 width=20) (actual time=24732.660..25420.858 rows=63368 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=285697 read=41423 dirtied=254 written=5765
               ->  Bitmap Heap Scan on customer  (cost=2907.42..41856.61 rows=139855 width=24) (actual time=4292.429..4667.968 rows=190621 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{23,21,32,26,10,24,18}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=35205 read=36871 written=5660
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2872.46 rows=139855 width=0) (actual time=4278.948..4278.948 rows=190621 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{23,21,32,26,10,24,18}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=18 read=36871 written=5660
               ->  Hash  (cost=406090.48..406090.48 rows=15104948 width=4) (actual time=20428.900..20428.900 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=250489 read=4552 dirtied=254 written=105
                     ->  Seq Scan on orders  (cost=0.00..406090.48 rows=15104948 width=4) (actual time=0.033..11391.893 rows=15015000 loops=1)
                           Buffers: shared hit=250489 read=4552 dirtied=254 written=105
 Total runtime: 25544.828 ms
(30 rows)

COMMIT;
COMMIT