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
				('21', '18', '13', '25', '11', '17', '31')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('21', '18', '13', '25', '11', '17', '31')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=693523.01..693523.02 rows=3 width=20) (actual time=14797.597..14797.598 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=244335 read=82252
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52886.87..52886.88 rows=1 width=4) (actual time=1009.888..1009.888 rows=1 loops=1)
           Buffers: shared hit=9 read=36333
           ->  Bitmap Heap Scan on customer  (cost=6642.16..51933.24 rows=381451 width=4) (actual time=150.644..901.007 rows=381888 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,18,13,25,11,17,31}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=9 read=36333
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6546.79 rows=381451 width=0) (actual time=138.243..138.243 rows=381888 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{21,18,13,25,11,17,31}'::text[]))
                       Buffers: shared hit=7 read=1057
   ->  HashAggregate  (cost=640636.06..640636.11 rows=3 width=20) (actual time=14797.527..14797.530 rows=7 loops=1)
         Buffers: shared hit=244333 read=82252
         ->  Hash Anti Join  (cost=596626.47..640193.94 rows=58949 width=20) (actual time=13739.295..14754.913 rows=63596 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=244333 read=82252
               ->  Bitmap Heap Scan on customer  (cost=2906.77..41854.26 rows=139790 width=24) (actual time=1082.133..1740.771 rows=190573 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,18,13,25,11,17,31}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=423 read=71625
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2871.83 rows=139790 width=0) (actual time=1069.781..1069.781 rows=190573 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{21,18,13,25,11,17,31}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=19 read=36870
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=12645.537..12645.537 rows=15015000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527872kB
                     Buffers: shared hit=243907 read=10627
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.037..5607.424 rows=15015000 loops=1)
                           Buffers: shared hit=243907 read=10627
 Total runtime: 14919.604 ms
(30 rows)

COMMIT;
COMMIT