Re: before image

Odba2003 wrote:

> the question of before image vs pre-image has to do with Automatic Undo
> Management. Here is the context:
>
> Oracle stores the before image of the data in special purpose UNDO tablespaces.
> Oracle also stores pre-images of data to enhance availability and read
> integrity for a query running in one session while another session is
> performing a dml transaction.
>
> I guess my question is, are before images the same thing as pre-images?

Go to http://tahiti.oracle.com and search for multiversion read consistency.

-- 
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace 'x' with 'u' to respond)