Re: Difference between Redo Log Buffer & Rollback Segment?

On Wed, 12 Aug 1998 02:27:34 GMT, violin.hsiao_at_mail.pouchen.com.tw (Violin) wrote:

>I'm a little confused about them.
>Could anyone tell me what the difference is between them?
>Thank you so much.... :)
>Please Cc to : violin.hsiao_at_mail.pouchen.com.tw

Rollback segments are used to rollback or "undo" transactions. They're also used to provide read consistency. I believe they contain both the before and after images of all changes made during a transaction. They also can be overwritten after the transaction completes (commit or rollback).

Redo logs are used for recovery. They're essentially a sequential, chronological, history of all changes made to the database. For example if you need to restore an old version a datafile, redo logs (both archived and online) are used to bring the restored datafile back in sync with the database.

HTH
--
Chuck Hamilton
chuckh_at_dvol.com

If at first you don't succeed, sky diving isn't for you. Received on Wed Aug 12 1998 - 10:41:19 CDT