RE: Oracle on windows and shadow thread file access

On UNIX, when a user process needs to access data, it will open the files of interest. The background processes 'attach' to all of the files when the OPEN state of the database is achieved. They do not open each file when they need to read/write. For example, CKPT attaches to the files and will maintain the handle as long as the process is running.

Why do I know this, you ask? One afternoon, a support tech moved a datafile since the device was 95% full. User queries would fail when trying to open the file, but checkpoints were succeeding and we could even dump the file headers without any problem. After discussing this situation with the SAs, we postulated that the background processes were keeping the files open and thus were still attached to the files original location. If we shutdown the background processes, the files would have been closed and the original blocks released. Once we resolved the issue, the support techs were scheduled for Oracle 101 training immediately!

On Windows, they handle files slightly differently and I am not sure.

-----Original Message-----
Sent: Friday, November 29, 2002 3:34 PM
To: Multiple recipients of list ORACLE-L

On Friday 29 November 2002 08:43, Jeff Herrick wrote:
> My understanding
> from the question was that he was wondering whether each
> user's process in a dedicated-server configuration opened
> all of the datafiles too

Maybe not all of the data files, but the users dedicated server process will open datafiles as needed to read data into the block buffer.

Now I don't know if I've helped any, or just added to the confusion.

Jared

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