Setting Up Journal Tables
Select the following journal options either at the database level or the table level. Specify single image or dual image journals.
The terms in Table 9 are used to describe journaling.
Note: Teradata Archive/Recovery Utility supports the generation of both before-image and after-image permanent journals, both of which can be either local or remote.
|
Journal Options |
Description |
|
After image |
The image of the row after changes have been made to it. |
|
Before image |
The image of the row before changes have been made to it. |
|
Dual image |
Two copies of the journal that are written to two different AMPs. |
|
Primary AMP |
The AMP on which the primary copy of a row resides. |
|
Fallback AMP |
The AMP on which the copy of a row resides. The Teradata Database distributes duplicate data rows to fallback processors by assigning the hash code of the row to a different AMP in the same cluster. |
|
Backup AMP |
The AMP on which copies of journal rows for nonfallback tables reside, including journals with single after-images, one copy of the dual after images, and one copy of the dual before images. Backup AMPs differ from fallback AMPs because journal images are not distributed to backup AMPs through a hashing algorithm. Instead, all images for one AMP go to a single backup. The backup for each AMP is always in the same cluster. For example, if AMPs A, B and C are in the same cluster, A backs up B, B backs up C and C backs up A. |