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Data file modification date [message #405042] Tue, 26 May 2009 03:08 Go to next message
linuxos
Messages: 31
Registered: April 2009
Member
I'm new in managing and designing oracle database.

After I performed some DDL/DML on the tablespace (e.g. create table, insert, update), I found that the datafile's modified date in OS is not changed. Only those redo log files and archived log files were changed.

Does it mean the data file was allocated enough space (not extended), and the file was opening or online fI/O processing?

But after I deleted a table, I found the date is modified. Why?

Thanks!
Re: Data file modification date [message #405052 is a reply to message #405042] Tue, 26 May 2009 03:33 Go to previous messageGo to next message
Michel Cadot
Messages: 64102
Registered: March 2007
Location: Nanterre, France, http://...
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Oracle data file dates are meaningless.

Regards
Michel
Re: Data file modification date [message #405059 is a reply to message #405052] Tue, 26 May 2009 03:48 Go to previous messageGo to next message
linuxos
Messages: 31
Registered: April 2009
Member
After I issued "COMMIT" after performing insert/update/delete/create table, etc., how can I know the data are written into the data files? Rather than using "SHUTDOWN IMMEDIATE", should I run "ALTER SYSTEM SWITCH LOGFILE" or something else?
Re: Data file modification date [message #405062 is a reply to message #405059] Tue, 26 May 2009 04:03 Go to previous messageGo to next message
Michel Cadot
Messages: 64102
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
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You cannot know and you don't need it.
Oracle guarantees the data are there, you don't need to know how it does this.

Regards
Michel
Re: Data file modification date [message #405069 is a reply to message #405062] Tue, 26 May 2009 04:16 Go to previous messageGo to next message
linuxos
Messages: 31
Registered: April 2009
Member
Thanks! That means I can export the data online without shutting down the database. But for user-managed backup, I still have to shutdown it to copy the data files.
Re: Data file modification date [message #405093 is a reply to message #405069] Tue, 26 May 2009 05:57 Go to previous message
Michel Cadot
Messages: 64102
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Quote:
That means I can export the data online without shutting down the database.

If "export" means Oracle export, you cannot export if the database is down. Export is like any other program, so if data are committed it sees them otherwise it can't.

Quote:
But for user-managed backup, I still have to shutdown it to copy the data files.

You can do it online if you are in archivelog mode and put the tablespace in backup mmode.

Regards
Michel
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