Author: David Ashlock

About once a week, our team gets a request from the server admins to provide some information on why a database server is running slowly. This typically begins a painstaking process of finding the main processes on the OS side and tracing them back to database sessions. Attached to this post (see bottom for link) is a general diagram that the team came up with for relating our tables together, taking RAC into consideration.

I decided to reprise my commentary on Oracle RAC and the gv$ views after reading Patrick’s comments on my previous post. It is always encouraging to know that someone is kind enough to read your work and provide insightful feedback – many thanks to him! There are two questions that I wanted to answer here: Can you use the gv$ views with a non-RAC environment? What do the WHERE clauses in a good block-checking script do?

I have experienced some pain at the hands of the Oracle RAC. My first encounter was about five months ago when I first became an “official” DBA. Being eager to jump into solving problems in my new job (as that’s what most DBAs do, solve problems), I relished the chance to get my hands dirty and work on a “real” DBA task — a database lock. Checking with a few knowledgeable co-workers, I was directed to a set of common database diagnostic scripts affectionately known as the “Pythian Kit”. his wasn’t the confidence-boosting exercise that I had anticipated.

I’ll preface this post with a note that the story itself is not really work- or DBA-related, but the lessons learned certainly are. I consider myself fairly conscientious when it comes to internet security and backing up my most important files (pictures of kids, music, etc), and I am diligent about taking at least a weekly backup of those files so that if (when) something catastrophic happens, I am ready. Once again, as my short life as a DBA has proven, theory and practicality rarely meet.

If you check out the “Butterfly Effect” on Wikipedia, you’ll find a rather interesting reference to, “sensitive dependence on initial conditions in chaos theory.” Fascinating use of phrase that probably doesn’t mean much to normal people until it happens to you. I could give you lots of theoretical examples, but perhaps a real-life one will make more sense.