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 ?
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
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 .