Wednesday, December 16, 2009

Quick Thoughts on DB2 Performance

Database performance problems are not caused by magic. Indeed, all performance problems are always caused by change. That statement flies in the face of what I normally say, which is “Almost never say always or never”… but in this case, it is true.

Think about it for a moment. If everything remains stable and unchanging in your environment, then why would performance vary? That’s right, it wouldn’t.

Something tangible must change before a performance problem can be experienced. The challenge of performance tuning is to find the source of the change, gauge its impact, and formulate a solution.

Change can take many forms, including the following:
  • Physical changes to the environment, such as a new CPU, new disk devices, or different tape drives.
  • Changes to system software, such as a new release of a product (for example, WebSphere, CICS, or even z/OS), the alteration of a product (for example, the addition of more or fewer CICS regions or an IMS SYSGEN), or a new product (for example, implementation of DFHSM). Also included is the installation of a new release or version of DB2, which can result in changes in access paths as well as utilization of new features.
  • Changes to the DB2 engine from maintenance releases and PTFs, which can change the optimizer (and sometimes introduce other new functionality).
  • Changes in system capacity. More or fewer jobs could be executing concurrently when the performance problem occurs. Or additional users may be banging away at your transactions.
  • Environmental changes, such as the implementation of client/server programs, the adoption of SOA, or other new technologies.
  • Database changes. This involves changes to any DB2 object, and ranges from adding a new column or an index to dropping and re-creating an object.
  • Changes to the application development methodology, such as usage of check constraints instead of application logic or the use of stored procedures.
  • Changes to application code, both SQL and host language code (COBOL, C, Java, etc.).

Although the majority of your performance problems are likely to be application-oriented, you must be prepared to explore any and all of these other areas when application tuning has little effect.

My advice is to be sure that you institute strict change control tracking across all areas of your IT infrastructure. That way, whenever you experience a performance problem, you will be able to track what has changed recently, along with who changed it and why. This is important because every DBA knows what the answer to the question “What changed?” will be… right?

It is always “nothing!”

And that cannot be true. Oh, it does not mean that the person answering is lying. He or she may not have changed anything. And it is not necessarily reasonable to expect an application developer to know what all could have changed…especially when what can impact DB2 performance spans so many areas of the IT infrastructure.

So do yourself… and your company a favor: be sure that you meticulously track each and every change to any aspect of your systems. Then – and this is where many shops break down – make sure that you have methods of tying all of the change information together in such a way that it can be queried and examined in the face of a performance problem.

Only then can you reasonably expect your DBAs rapidly to be able to track down and remedy DB2 performance problems… because only then will they have the pertinent information at their disposal.

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Wednesday, December 02, 2009

Wordle of my DB2 Portal Blog

Wordle: DB2 Portal Wordle The "jumble" of words shown here is a Wordle, which is a "word cloud" of text. I fed my blog location into the Wordle generator and it created this pretty picture based on the words I most commonly use here in this blog.

The cloud gives greater prominence to words that appear more frequently in the source text. No surprise that "DB2" and "data" dominate the other words!

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Monday, November 02, 2009

New DB2 Twitter List

Just a very quick post this morning to let all you DB2 Twitter folks out there know that I created a list of the DB2 tweeters I know about at

If you are a DB2 professional and I left you off the list please leave a comment here or drop me an e-mail and I'll be happy to add you.

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Thursday, July 30, 2009

Discount on IBM Information on Demand Conference

The IBM Information on Demand (IOD, for short) conference is rapidly approaching. The conference will be held in Las Vegas, Nevada the week of October 25 – 30, 2009 at the Mandalay Bay casino and hotel.

The IOD conference is IBM’s signature event for their data and information management product lines. By attending IOD 2009 you can gain unique perspectives from IBM experts, technical leaders and visionaries as well as peers in your industry. Many of the developers of IBM’s offerings, such as DB2, Informix, and IMS, will be delivering educational sessions at IOD. And over 200 customers will share real-world experiences detailing how they have unlocked the value of their information and realized tangible and immediate return on investment.

OK, so what about that discount? IBM has been kind enough to provide me with a discount code that I can share with my readers. You will need to provide the code, G09MULL, when your register for the conference and you will get a $100 discount off of your registration!

Here’s how to register on-line:

  • An IBM userid and Password are required to register. If you have an existing account ID, please select 'Register for the Conference' and sign on. If you do not have an account ID, please follow the link 'MY IBM ID' to obtain one. Complete the form and click 'SUBMIT'. You will then be allowed to continue as a registered IBM user. Click 'Continue' and select 'Register for the Conference' and sign on with your new userid and password.
  • Select registration type of 'Customer' and click 'Continue'
  • Complete the appropriate fields on the enrollment form
  • Under the 'Promotion Code Information' section, enter PROMOTION CODE G09MULL. You must enter this code to receive your $100 discount.
  • Complete the form with attendee, arrival and payment information clicking 'Continue' at the bottom of each section.
  • Click 'Submit Registration'

Note: Credit card information is required to guarantee your registration regardless of your method of payment and/or discount amount.

That’s all there is to it. And you can use the promotion code multiple times for all of the folks at you company that will be attending the Information On Demand conference in 2009.


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