Adding datafile automatically when tablespace is 90% full

Question

Hi,
I have a tablesspace having a name user01.dbf(Auto extensible to 4 GB) user02.dbf(Auto extensible to 4GB) ..........
I am just thinking about automatically creating datafile(alter tablespace add datafile).
1. (total number of datafiel in tablespace) *4 - space used by dba_segments belonging to user tablespace. if it returns less then 1 GB space, then add a datafile.
And I will put it on CRONTAB. and it will run every 24/7.
Does not this look weired?
Advice:
1. Don't we have any option like the database server will trigger an event when it is 90% and I can trap this event and run a command to add a datafile. I know internally it will do the same but still I feel if you have a feature then why not use it.
Any information will be helpful in this regards. And the same question is for OS level do I have to check it every second, space on the file system?

Answer 1

Do one thing ,write a script which will check free space of your tablespaces like..
SELECT NAME FROM V$DATABASE;
select to_char(sysdate,'dd-MON-yyyy hh:mi:ss')Snap_ShotTime from dual;
SELECT Total.name "Tablespace Name",
nvl(free_space, 0) free_space,
nvl(total_space-free_space, 0) Used_space,
total_space
FROM
(select tablespace_name, sum(bytes/1024/1024) free_Space
from sys.dba_free_space
group by tablespace_name
) free,
(select b.name, sum(bytes/1024/1024) TOTAL_SPACE
from sys.v_$datafile a, sys.v_$tablespace B
where a.ts# = b.ts#
group by b.name
) Total
WHERE free.Tablespace_name(+) = Total.name
AND Tablespace_name <> 'PERFSTAT'
ORDER BY Total.name;
and find the %age of used space Vs free space.Enable your mail server which will send you the alerts.
Put in crotab file and set them accordingly..
Pratap