Necessary to me to increase datafile SYSTEM

Hi all! Help me please.
It is necessary to me to increase a size of datafile SYSTEM.
I changed a size of another datafiles. Whether there are any differences
in this case? Should i do it when DB is open or only mounted?
Thank you in advance.

Don't worry.
You can resize the datafile for SYSTEM or create another datafile to increase size.

absolutly db opened, alter tablespace system add datafile '****' size ****

Do you know the reason the tablespace has to be resized? Are you sure nobody has system as their temp tablespace or default tablespace?

Either resize the dbf or set AUTOEXTEND ON for the system dbf.

I know the reason the tablespace has to be resized .
The former dba created some users which had system both default
and temp. I changed their default and temp tablespaces but they
have some tables there which grows and grows...
I can't add datafile as number of datafiles=db_files in init.ora.
I'll do as you wrote.
Thank you.

hello,
I have a question,if by resizing any tbsp,fragmentation occur?I always prefered to add datafiles rather than resizing as I thought it would fragment the tbsp more.am I right?

hello,
I have a question,if by resizing any tbsp,fragmentation occur?I always prefered to add datafiles rather than resizing as I thought it would fragment the tbsp more.am I right?

also tatyana can't U alter those fast increasing tables default and temp tbsp to other tbsp.except datadictionary nothing is required to stay in system tbsp,especially user tables should not.

Yes, if you resize a datafile then it's possible that it could fragment the file on the disk.

I resized system .
Thanks to all.
drishti, now nobody have system as default or temp but
i can't move existing tables to another tbs.

Yes, you can. Either by export/import or by transportable tablespaces (O8i). I don't know about those, but I've definitely tried the first one and it worked.

Good luck!