Friday, May 21, 2010

Traditional vs OLAP

I have been following a very interesting thread on LinkedIn in the group called Data Warehouse & Business Intelligence Architects. The thread is discussing the pros and cons of OLAP as compared to more traditional methods of modeling. Personally I love these discussions. Here's what I recently said:

For me, probably an oldie in terms of these discussions, I have been working with modeling and data warehouses coming up on 25 years. I find it very, very strange that for some reason the term OLAP gets pushed around as if it is the answer to everything. This is probably being unfair to the technique because it's actually been around in one form or another a lot longer than most people realise.

Long before the term was invented or, more to the point shall we say, the technique was discovered, documented and given a formal name, we have been able to model enormous data warehouses with enormous amounts of data. Databases with terabytes of data are not new.

If I'm following the thread correctly I see two schools of thought, one pushing OLAP as the bees' knees and one pushing relational modeling. As someone who entered this field not too many years after Dr. Edgar Codd was first touting his ideas to IBM I can tell you that if a relational model is done correct with the right partitions, indexes and joins I can design a data warehouse using traditional methods for far less money than most folks would have you believe it should cost.

I'm somewhat of a historian and I actually have in my possession a set of Dr. Codd's early drafts. It makes for fascinating reading. So to anyone who is not sown on the idea yet I would urge you to read one of the many good books on the subject. You can do no worse than start with one of Ralph Kimball's books but you might also want to look at Bill Inmon.

Personally, I don't adhere strictly to any of the father's of data warehousing. I have read them all and I mix and match as the situation arises replete with a little tangential leap from time to time, sometimes of faith but mostly based on experience. Oh yes, and occasionally I mix them all, you know, just for fun because, after all, this is a beautiful world and we are in a beautiful profession and we have beautiful problems to solve.

So, what do you think? Are you a purist, a traditionalist or a modernist, somewhere in between or an amalgum of all three?

1 comment:

LewisC said...

I completely agree with you. I've been doing warehousing off and on for 15 years and while I generally stick to established norms (I stand on the shoulders of others), I take the best I can find from Kimball and Inmon (and a few others).

There's rarely any reason to reinvent the wheel but there are many reasons to experiment with new materials and processes to create the wheel.