How an IBM DB2 LUW DBA Prepared for the OCA Exam
September 20, 2010
Can an IBM DB2 DBA learn Oracle? Follow one DB2 DBA as she prepares to take the Oracle Certified Associate Examination.
As a consultant, I am always in learning mode. Usually, I'm learning a new release of DB2 or how to prevent a new security exploit. Recently, I decided to focus my energy on Oracle. I've always known a "little" about Oracle, but now, I wanted to learn more.
I know many DBAs don't see value in certifications, and I understand the argument. Even though I agree that product experience is the better teacher, prepping for a certification helps me ensure that I learn enough about the product to avoid 'testing jitters'. Based on personal experience, I know that studying for an exam means that I over-prepare and learn more than I would have if a test had not been looming. When I was first learning DB2 (more than a few years ago), I found that preparing for a certification exam forced me to find quality study time because I don't like to flunk tests.
I thought that the Oracle Certified Associate designation, which requires passing two tests, would be a realistic goal since it is the first level of certification offered for Oracle Database Administrators. I did get one break. A few years ago, I did some Oracle to DB2 conversions. As part of that work I learned enough about Oracle to take and pass exam 1Z0-007, "Introduction to Oracle9i SQL". After checking the Oracle certification requirements, I found that having passed this exam would count as credit for the first of the two required tests necessary to attain the OCA certification.
With only one test to go (1Z0-052, Oracle Database 11g: Administration I), I thought I could probably just take a class and sit for the second exam. As I quickly learned when I attended an Oracle University class, that assumption turned out to be a delusion. The Oracle Database 11g: Administration Workshop 1 (http://education.oracle.com ) convinced me that I would need a lot more preparation than I originally thought.
What I eventually discovered was that I probably would have a more difficult time passing the exam than most new Oracle DBAs. Why? My DB2 knowledge would actually hinder me. When I started this journey, I didn't realize I'd almost have to "unlearn" what I know about DB2 in order to clear my mind before tackling the necessary concepts to pass the OCA exam.
I had originally decided that my approach to this effort would be to treat this exercise as I might if I needed to learn a new language. I would build on the knowledge I already had about DB2 databases and then just translate that to "Oracle". I found some big stumbling blocks early in that effort. For example, the terms "instance" and "database" are near and dear to my DB2 LUW database heart, but they conjure different mental visions when discussing these terms with Oracle DBAs. Obviously, memory structures would be different as well, which would mean tuning would be different, which would mean…well, you get the picture.
While the fundamentals between DB2 and Oracle seem to correlate well (after all a database by any other name must have certain fundamental functionality in order to achieve market prominence), the terms used to describe that functionality do not need to be identical. Database functionality is important, the ability to consistently produce correct results is important, but the actual names for the descriptive terms are trivial until you need to learn what those terms represent. So, there I sat, with some strong mental images of DB2 terms and the concepts they represent to a DB2 DBA, and realizing that those terms did not necessarily represent similar concepts from the Oracle standpoint.
To DB2 DBAs an Instance is not "the Database". I think of the instance as the outer circle of resources and control, with the database(s) living inside the circle. Sure, I can have more than one instance on a machine and I can choose whether each instance has only one database or several. The instance is created first, started (db2start) and any associated databases can then be created. Once a db2start finishes its task, any databases that have already been created in that instance are ready for connections.
The Oracle world takes a slightly different approach with these terms and I did not have a good DB2-to-Oracle translation tool to use, so I struggled to make sense of the Oracle meanings. The Oracle instance is started, yes, but there are several options. That's when then the DB2 to Oracle knowledge translation really got fuzzy for me. The Oracle instance is "associated" with a specific database and the database has to be mounted and opened before users can access it. The Oracle instance uses locks to manage internal consistency. In DB2, locks are managed in the database. Processes connect and disconnect from the Oracle instance, but with DB2, connections are made to the database. Well, I thought, this is not going to interpret well into my DB2-centric mindset.
Of course, there are terms and concepts that are similar between the two. Crash recovery, for example, proceeds through a comparable course of events for both platforms. The important concepts were there, but the approaches and those darn terms were different enough to challenge me. So, after realizing this was not going to be easy, I began my search for more information.
While I am still looking for that DB2 to Oracle Rosetta stone, the good news is that I found some terrific resources for learning the material. That made my "transition" easier.
If you are preparing for an Oracle certification, valuable information can be gained for free on the following sites:
Take a trip to Tahiti, or rather Oracle's version of Tahiti.
A list of the exam topics that are tested on the exam covered are located at Oracle Certification Program
Oracle Learning Paths can be found at Oracle Database 11g: Database Administrator (New) - Learning Paths
Exam testing tips can be found at Hints on OCA/OCP exam technique
The following resources are also very helpful, but are not free:
An Oracle IZ0-052 practice exam can be purchased from Kaplan Selftest
I also found several great Oracle books on Safari Books Online and added them to my bookshelf.
My favorite Oracle book is "OCA: Oracle Database 11g Administrator Certified Associate Study Guide: (Exams1Z0-051 and 1Z0-052)" by Biju Thomas.
With all these resources, how could I go wrong? Unfortunately, resources are only good if you have time to review them.
As I write this article, I still don't have my OCA. In keeping with the theory that the only constant is change, my job responsibilities changed dramatically shortly after I made the commitment to complete my OCA and write this article. As a result, I've had to temporarily give up my evening Oracle OCA study time in favor of evening "paying work" time. Soon, I should be able to resume my studies and (I hope) finally see that OCA certificate with my name on it. I will hang it on my cubicle wall, next to my DB2 certifications and my CISSP certification (near the black velvet Sad Clown painting). Yes, it's true, I do want to wallpaper my cube with certifications. Doesn't every consultant?
Maybe in a few weeks, you will be taking an Oracle certification exam and see a fellow test taker, proudly wearing her IBM Information Champion lapel pin, as she attempts the exam that will show whether her preparation for the OCA exam was successful or not. No need to wish her luck. She will be prepared.