Re: What is an edition?
Date: Wed, 05 Nov 2008 09:39:03 +0100
Michael Austin wrote:
> I could be wrong and not having done very much research (only what has
> been explained here) it appears to resemble something from the
> Oracle/Rdb product (formerly DEC/Rdb) where it would be used to
> "version" an object whereby a new "version" is generated when you make
> ddl changes to an existing object. This allows for those on-the-fly
> changes like rolling upgrades. ie: InstanceA on nodeA has been upgraded
> using edition "2" while InstanceB on nodeB is still using
> edition/version "1". Simply bouncing node2 effects the upgrade.
> The UNIX environment has a long way to go to catch up to the REAL high
> availability features or the DEC- now HP OpenVMS - such as file
> versioning - which is where Rdb got the concept to be able to do real
> rolling upgrades of databases.
After posting this, I had a phone conversation with a friend in the know who told me that this is a part of the "rolling upgrade" feature. Essentially, in order to upgrade one node to the new version whilst allowing the other nodes to run the old version of the dictionary, you need to have both versions running concurrently. How can you tell between the versions ("editions") of the data dictionary? You introduce "edition objects" and add an argument to sys_context function to enable it to discern among the different editions. That can be guessed from the ML document 565413.1 which explains how DBA_SOURCE view was altered to include the sys_context function. Michael, previous experience with RDB is obviously a valuable thing. Unfortunately, I haven't had any. Also, thanks to Maxim Demenko, I learned that Dan Morgan has partly documented this feature at: http://www.psoug.org/reference/editions.html. Thanks to everybody.Received on Wed Nov 05 2008 - 02:39:03 CST