Re: A database design question

Dan,
I was the data architect for a large multi-release banking project. My objective was to have a 'as normalized as possible' database. However a couple of key factors come in play.
1) Performance
Each database service costs you. If you take 0.2 seconds (banking industry average DB access time used for estimations). I came to the conclusion that for data that is quite static, such as parameters like interest calculation mmethods, interest floor and caps, product definitions, etc. we should denormalize appropriately to minimize the database services or joins required t obtain a data set. For data that is not static, say a savings account, one has to be really careful about denormalization because some portions of an application will benefit fromit, however some other portion that needs to update denormalized data will suffer. Each denormalization has to be evaluated case by case with a thorough understanding of the imlications.
2) Multi release large project environment. In my large project (manpower approx 200) application design was changing rapidly due to changes in functionality and change in scope. This caused certain portions of an application to be coded, however another application was being developed that required the DB design to support additional & different functionality. This very soon results in denormalization in view of manpower and budget constraints. Typically in multi release large projects the functionality& scope of future releases is not fully confirmed, thus making it very difficult to design a nice normalized database. As you move on to the next release ther is the tendency to fit things in to the previous design - again budget constraints come into play. The resulting database designat the end of a multi release project is never in a fully normalized form, although thats what it shoul be in an ideal situation.

Cheers

Dan Townsend <townsend_at_ebmud.com> wrote in article <33E234DC.9E3_at_ebmud.com>...
> On Wed, 30 Jul 1997 15:07:04 -0500, Sanjay Rallapally
> > <c696346_at_showme.missouri.edu> wrote:
 

> >
> >Its me again,
> >I am curious abut the level of database&nbsp; normalization that is
> >followd in the real-world . How rigidly do u guys follow the database
 design
> >rules regarding normalization? Lastly, when is it better to have an
 unnormalized
> >table, than an unnormalized one? I mean, how useful are indexes as
 against
> >having a normalizzed table
Received on Sun Aug 03 1997 - 00:00:00 CDT