It’s been about a year since Oracle decided to change their database version schema, from version with a couple of releases (e.g. 12.1 is 12cR1 and 12.2 is 12cR2) to a single annual version (e.g. 18c and 19c). Now, when 18c is stable and 19c is here on the cloud and Exadata and almost here on-premises, I thought it’s a good time to revisit this topic.
I had a bad night last Thursday.
After patching two test RAC databases and one production RAC with 180417 DB Bundle Patch (and some one-offs), I got to the point where it was time to update the most critical RAC system.
We were really looking forward to this as we had hit a few bugs that this DBBP and one-offs should fix. But boy, did that go wrong…
Lately I started patching a client’s database (220.127.116.11) to the latest PSU (180417). This is a RAC environment with streams and all kind of other features, so over the time we hit quite a lot of different bugs. When we planned this PSU (we installed the bundle patch version), we added about 7 one-off patches (some are recommended by Oracle and some we had to add because the bugs affected us quite badly).
In February ’17 I participated in Mike Dietrich’s upgrade workshop and it was great! I don’t want to repeat stuff that he said there, you can read everything on his blog. This workshop made me think about upgrades I did in the past (and I did quite a few) and important things to think about before and after upgrading a database.
When Oracle releases a new version or even a petchset, sometimes they change the default value of initialization parameters or add new features and introducing new parameters with them. These changes affect the behavior of many components. In this post I’d like to address how I deal with parameter of features changing optimizer behavior. Continue reading “Optimizer Changes After Upgrades”