Permanent Journal

Database
Enthusiast

Permanent Journal

Hi All,

Can any one please explain me .

what is dual image and single image?

if a table have a  both ,before and after PJ configured is called dual image ? 

if any, after or before PJ congfigured is called single image ?

2 REPLIES
Enthusiast

Re: Permanent Journal

Hi, in case of dual image, 2 copies of the row which is undergoing a change will be stored. while for single image, only one copy is stored in PJ.

If a table have both BEFORE AND AFTER Journal, it does not mean dual image. If you have DUAL BEFORE JOURNAL or DUAL AFTER JOURNAL or both then its called a dual image.

For a single image, either a BEFORE JOURANL or AFTER JOURNAL is enough.

But if you have a single image for a Fallback protected table, The Fallback functionallity makes it a dual image.

Please refer the below link to get more idea- http://forums.teradata.com/forum/database/permanent-journals

Enthusiast

Re: Permanent Journal

so a table having journal  and fallback protection is called dual image right ?

and what is purpose of having 2 copies of row which is undergoing a change. how this can be used?

is PJ is same as Tj.which is going to take a sanpshot of only the rows which are going to be changed or it will take a whole snapshot of the table.and what could be the size of the snapshot is it same size of the base table/row

thanks for you time .