Hot cloning PDBs is new in 12.2, so you don’t have to put the source PDB into READ ONLY mode before the cloning if you have it in local undo mode. I suppose shared undo mode will become very unpopular. Another 12.2 New Feature is the option to clone a PDB that can be refreshed from the source PDB. I will show both features with this article, but you may of course do hot cloning without a later refresh. In this case, just leave out the REFRESH MANUAL clause and you don’t have to OPEN READ ONLY the cloned PDB afterwards. On a high level, what I demonstrate is this:
Before describing the issue that lead to this post, let’s shortly review how the handling of initialization parameters works in a multitenant environment.
A logical error happened in one Pluggable Database. A PDB Point-In-Time-Recovery rewinds it while the others remain available and stay as they are.
Now that I got myself a bit acquainted with the Database as a Service offering,…
This is how an upgrade with pluggable databases looks conceptually:
You have two multitenant databases from different versions in place. Preferably they share the same storage, which allows to do the upgrade without having to move any datafiles
You unplug the pluggable database from the first multitenant database, then you drop it. That is a fast logical operation that does not delete any files
Next step is to plug in the pluggable database into the multitenant database from the higher version
It’s been over 2 years since 12c was released and there still seems to be a lot of confusion about the pluggable database stuff. I think most people know the top-level concept, there’s only so many times you can see the memory stick analogy before it gets burned on your skull, but that doesn’t do much to help with the reality of working with it day-to-day.
Thank you for attending my session RAC'fying Multitenant at Oracle Open World 2014. You can download the slide deck here.
[Updated] Oct 4th, 2014: The article on multitenant I wrote for OTN is available here. http://www.oracle.com/technetwork/articles/database/multitenant-part1-pdbs-2193987.html. This article shows various commands I referenced in my session, e.g. point in time recovery of PDBs.
As always I would love to hear from you.
This a a little discovery from my present Oracle Database 12c New Features course in Copenhagen: The default setting for Controlfile Autobackup has changed to ON – but only for Multitenant, apparently:
I forgot to mention, I put another multitenant article live at the weekend.
I’m not sure I will ever use it, but it’s good to know it’s there.
I was originally working on an article on a completely different multitenant feature, but the examples I was using highlighted a bug, which kind-of scuppered that article. I’ve raised an SR and I’m waiting on the acknowledgement and possible fix. I’ll hold that article back until the fix is in place.