Kbase 15421: Can you use a V6 After-Image file on a V7 Database?
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
5/10/1998 |
|
Can you use a V6 After-Image file on a V7 Database?
IS IT POSSIBLE TO ROLL FORWARD VERSION 6 AFTER-IMAGE (ai) FILE
ON TOP OF CONVERTED V7 DATABASE? If so, then one could
convert when the V6 database is in use.
No, it is not possible. The ai format is different between
V6 and V7. Also, there are record types in V6 ai files that
do not exist in V7 and vice-versa. V7 does not know what to
do with the V6 record types it does not have.
After-image records are *physical* redo log records that
describe previously made changes to a database. They describe
changes to make to particular versions of database pages
(blocks). Each change updates a page to the next
version. For example, there are records describing
operations like "insert the following 56 bytes into
record slot 21 on version 67 of page 6435", "delete 33
index bytes from version 789 of page 8765", and
"make version 34 of page 3921 into a free page".
You can only roll forward if the physical contents of the
target database match exactly the physical contents and page
version numbers that existed in the source database when the
ai file was begun. So even if the databases are the
same version, you cannot roll forward from one database
to a different one.
Gus Bjorklund, Developer
REVISED: January 1996
Progress Software Technical Support Note # 15421