Rollback Question

[lesstjm]

I am studying for the Architecture and Administration exam and I want to make sure I have this correct. You have the Redo Log Buffer which holds the Rollback Segments which are written to the Redo Log Files by the LGWR process. Then when they hit a certain mark, which is determined in your parameter file, a log switch occurs. Is this correct? Do you have anything else in the Redo Log Buffer?

[sambavan]

When the redo logs fills up or when the check point time is reached, thats when the log switch occours. Which ever comes the first.

Good luck.
Sam

[adrianomp]

Redo log buffers do not hold rollback segments, they are different structures. Redo log buffers are written to redo log files when:

- buffers are 1/3 filled
- every three seconds
- a DBWn proccess writes modified buffers to disk

,what happens first.

Log switch occurs when a redo log group is filled, or enforced manually if needed by ALTER DATABASE SWITCH LOGFILE. I think the initialization parameter you were talking about is LOG_BUFFER, it is related to writing from redo log buffers to redo log files, not log switch.

Yesterday there was a thread about the difference between redo log files and rollback segments. Maybe you should look at it.




Adriano.

[sambavan]

Check this thread,

[url]http://dbasupport.com/forums/showthread.php?threadid=7651[/url]

[lesstjm]

Thanks for your link sambavan it helped.