Multitenant : It’s easy to screw up!


multitenantSome things happened to me yesterday which I thought I would pass on, in case it helps others. This is not necessarily a criticism of the Multitenant architecture itself, but more about my misuse of it. 🙂

I’ve complained numerous times about the inclusion of the shared APEX installation used with the Multitenant option. I’m sure it is great for some companies that provide APEX as a service, but it’s not the right option for me. I would typically recommend removing it before you create a PDB, as described here. So what did I do yesterday? I banged out a script as a variant of a non-CDB build and totally forgot about the shared installation. When everything was finished I patted myself on the back, then noticed my mistake. 🙁 I had to remove the PDBs from 3 instances, remove the shared APEX installations, the recreate the PDBs. Luckily it was early on in the process, so it wasn’t a great drama. It would have been significantly more annoying if I hadn’t noticed for a few days!

Next up I nearly cloned a PDB, which would have left me with 2 PDBs in the instance, and potentially a big bill for the Multitenant option. I was literally about to hit the return key when I realised what I was doing. 🙁 Needless to say I immediately added a trigger to all my instances to prevent any future stupidity on my part. You can see what I did here. As I say in the article, I’m not sure if there is some hidden long term tracking of the maximum number of PDBs in a CDB, but I’m a paranoid type… 🙂

As an aside, I also noticed that when I add a new PDB to a CDB it takes Cloud Control 13c a long time to notice the PDB is there. I did try to give it a nudge by doing the following, but it didn’t seem to notice.

  • Highlight the CDB in the database target list.
  • Click the “Configure” button.
  • Scroll down and click the “Sync Pluggable Databases” button.

It didn’t recognise the change, even though it was clear in the V$PDBS and CDB_PDBS views. Not sure if this is normal or if I just got unlucky. Everything looks OK now… 🙂



Author: Tim...

DBA, Developer, Author, Trainer.

2 thoughts on “Multitenant : It’s easy to screw up!”

  1. Hello Tim,

    There’s a new feature in 12.2 about which I’m not well aware – it’s Lockdown Profiles.
    I was unable to visit OOW2016 but I read that using lockdown profiles we can disable certain features and options in a PDB.
    But maybe I’m totally wrong here because these are my pure assumptions based on the information I read in some presentations and over the Internet.

    PS: I accidentally commented to the “Multitenant : Prevent Accidental Creation of a Pluggable Database (PDB) – Lone-PDB” article but then I found that you may not expect my comment there. I thought so because after I sent my comment, the message “DO NOT ask technical questions here! They will be deleted! ” was shown.

  2. Mikhail: LOL. I saw the comment and left it because I thought it was relevant. 🙂

    I’ve heard of the Lockdown Profiles. I got the impression they were about locking down the functionality within a PDB, not locking down functionality at the root level. I guess we will find out once the full product is released. 🙂 It will be good if there is a “proper” method to control this.



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