Back to Oracle

Category: UpgradingOracleDatabases

In Extreme Programming Explained (2nd edition), Kent Beck references Pramod Sadalage's elegant incremental design strategy:

• Start with an empty database.


• Add all the tables and columns with automated scripts that also migrate any existing data as necessary.


• Sequentially number the scripts so a database at any earlier stage can be brought up to any later stage by running the scripts.

This idea is extremely (pun intended) similar to my own thoughts on the same problem, though I think it misses a couple of points. I'd prefer to see it written more like:

• Start with an empty database.


• Add all the tables and columns you need for the current piece of work with automated scripts that also migrate any existing data as necessary.


• Surround each script in tests that cover the pre and post conditions. The pre conditions cover your assumptions about the database required for the script to run, the post conditions cover the requirements for regarding the script as 'complete'


• Sequentially number the scripts so a database at any earlier stage can be brought up to any later stage by running the scripts.


• Make sure a failure in any script (including its pre or post) stops the rest of the patches from running


• Make sure you can run all the patches from a single command

If the system you're developing sits on top of a legacy system then your build will start with an import of a set of live data into an empty schema, the upgrade as covered above and then the tests for the rest of the application can run against a system that closely mirrors the target environment.
If the live data is so huge it takes to long to do the upgrade as part of the regular build you've got three options:

• Tune the upgrade so that it is quick enough


• Reduce the set of data you import so you have the right texture of data on a smaller scale


• Run the full import and upgrade in a less frequent build

Ok, ok, so it might not be so elegant as Pramod's way of putting it, but it's complete...

Aside: If you've not read XP Explained, read it NOW. If you've read the first edition, but not the second, read the second edition NOW. If you've read both, think about reading them both again!

Technorati Tags: oracle, extreme+programming, Kent+Beck, Pramod+Sadalage

Developer Factory

Gotta say, I'm enjoying Object Thinking. David West is a bit of an evangelist but it's difficult to argue against many of his points.

One such point is that eXtreme Programming isn't about creating high quality software, it's about creating high quality developers. The by-product of having high quality developers is that high quality software is produced. I'm worried that tight fisted IT Managers might get their hands on this thought and start charging training costs to employees for working in an XP environment, but it is a good thought none-the-less.

It's also something that each developer should bear in mind when working in that XP environment. Every piece of work that's done is an opportunity to become a better developer. You're in full time training. Sometimes you're the trainer, other times you're the student. Most the time you're both. By sitting back and explaining certain assumptions you find flaws in the those assumptions. By teaching people what you do and how you do it, you spot problems more easily. Plus, of course, there's someone sat next to you that will tell you when you're wrong.

It's a thought I've always had lingering in the back of mind, but it's probably always been 'Me Teacher, You Student'.
I'm wrong, and I need to learn to change that attitude. We're all learning and improving the way we work through our interactions with other.

When we forget that we've got a lot to learn then we start going backwards again.

Technorati Tags: extreme+programming, David+West, pair+programming

Good conversations...

There's one going on over here.

Code found wanting...

function _processMenuItem( &$oMenu
                         , $oMenuItemElement
                         , $sMenuData
                         , $bSelected = false ) {
  
  
 // TODO: Sort this out, it sucks!
 global $IMAGE_PATH;

No shit Sherlock.

Bobablog hits Google

It's finally happenned. The outside world (Google) has finally found me. Fair enough, a search for Robert Baillie still brings up some 17th century scottish 'divine' from Jarviswood... but search for Bobablog.

Just try to stop me now!

Google

Technorati Tags: bobablog