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
				('15', '30', '31', '28', '34', '22', '23')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('15', '30', '31', '28', '34', '22', '23')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691175.77..691175.78 rows=3 width=20) (actual time=10157.948..10157.948 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=323998 read=1593
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52911.96..52911.97 rows=1 width=4) (actual time=468.588..468.589 rows=1 loops=1)
           Buffers: shared hit=35287 read=1056
           ->  Bitmap Heap Scan on customer customer_1  (cost=6648.35..51956.68 rows=382108 width=4) (actual time=90.875..392.872 rows=381774 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,30,31,28,34,22,23}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35287 read=1056
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6552.82 rows=382108 width=0) (actual time=82.614..82.614 rows=381774 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{15,30,31,28,34,22,23}'::text[]))
                       Buffers: shared hit=9 read=1056
   ->  HashAggregate  (cost=638263.74..638263.78 rows=3 width=20) (actual time=10157.847..10157.848 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=323995 read=1593
         ->  Hash Anti Join  (cost=594271.01..637821.64 rows=58946 width=20) (actual time=9845.136..10140.386 rows=63518 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323995 read=1593
               ->  Bitmap Heap Scan on customer  (cost=2911.87..41869.59 rows=140180 width=24) (actual time=520.665..675.871 rows=191024 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,30,31,28,34,22,23}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35173
                     Buffers: shared hit=70470 read=1593
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2876.82 rows=140180 width=0) (actual time=513.434..513.434 rows=191024 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{15,30,31,28,34,22,23}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35297 read=1593
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=9205.311..9205.311 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=253522
                     ->  Seq Scan on orders  (cost=0.00..403671.84 rows=15014984 width=4) (actual time=0.024..4209.970 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Planning time: 3.908 ms
 Execution time: 10164.204 ms
(34 rows)

COMMIT;
COMMIT