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
				('18', '12', '32', '14', '25', '23', '28')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('18', '12', '32', '14', '25', '23', '28')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693714.54..693714.55 rows=3 width=20) (actual time=16395.081..16395.082 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=325360 read=1242 written=12
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52988.20..52988.21 rows=1 width=4) (actual time=789.581..789.581 rows=1 loops=1)
           Buffers: shared hit=35594 read=749
           ->  Bitmap Heap Scan on customer  (cost=6682.59..52029.28 rows=383569 width=4) (actual time=177.512..663.145 rows=381757 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,12,32,14,25,23,28}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35594 read=749
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6586.70 rows=383569 width=0) (actual time=155.651..155.651 rows=381757 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{18,12,32,14,25,23,28}'::text[]))
                       Buffers: shared hit=316 read=749
   ->  HashAggregate  (cost=640726.26..640726.30 rows=3 width=20) (actual time=16394.999..16395.002 rows=7 loops=1)
         Buffers: shared hit=325358 read=1242 written=12
         ->  Hash Anti Join  (cost=596664.30..640277.97 rows=59771 width=20) (actual time=15443.244..16342.836 rows=63466 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=325358 read=1242 written=12
               ->  Bitmap Heap Scan on customer  (cost=2944.60..41917.24 rows=140748 width=24) (actual time=893.500..1280.162 rows=190619 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,12,32,14,25,23,28}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=70821 read=1242 written=12
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2909.42 rows=140748 width=0) (actual time=880.412..880.412 rows=190619 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{18,12,32,14,25,23,28}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35761 read=1130
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=14532.149..14532.149 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=254534
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.026..6639.820 rows=15015000 loops=1)
                           Buffers: shared hit=254534
 Total runtime: 16596.963 ms
(30 rows)

COMMIT;
COMMIT