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
				('19', '10', '23', '24', '21', '33', '17')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('19', '10', '23', '24', '21', '33', '17')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=691116.28..691116.29 rows=3 width=20) (actual time=10455.149..10455.150 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=323977 read=1593
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52887.37..52887.38 rows=1 width=4) (actual time=441.063..441.064 rows=1 loops=1)
           Buffers: shared hit=35284 read=1057
           ->  Bitmap Heap Scan on customer customer_1  (cost=6643.14..51933.78 rows=381434 width=4) (actual time=83.408..367.121 rows=382083 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,10,23,24,21,33,17}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35277
                 Buffers: shared hit=35284 read=1057
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6547.78 rows=381434 width=0) (actual time=75.156..75.156 rows=382083 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{19,10,23,24,21,33,17}'::text[]))
                       Buffers: shared hit=7 read=1057
   ->  HashAggregate  (cost=638228.83..638228.88 rows=3 width=20) (actual time=10455.078..10455.080 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=323974 read=1593
         ->  Hash Anti Join  (cost=594267.78..637782.86 rows=59463 width=20) (actual time=10163.488..10437.651 rows=63456 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=323974 read=1593
               ->  Bitmap Heap Scan on customer  (cost=2908.64..41858.10 rows=139865 width=24) (actual time=492.321..620.093 rows=190661 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,10,23,24,21,33,17}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35156
                     Buffers: shared hit=70449 read=1593
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2873.67 rows=139865 width=0) (actual time=485.097..485.097 rows=190661 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{19,10,23,24,21,33,17}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35293 read=1593
               ->  Hash  (cost=403671.84..403671.84 rows=15014984 width=4) (actual time=9411.312..9411.312 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=0.033..3946.950 rows=15015000 loops=1)
                           Buffers: shared hit=253522
 Planning time: 3.678 ms
 Execution time: 10473.228 ms
(34 rows)

COMMIT;
COMMIT