[thelist] mapping out an oracle database

[Jeremy Weiss]

On Thu, Feb 25, 2010 at 7:07 PM, Martin Burns <martin at easyweb.co.uk> wrote:
>
> On 25 Feb 2010, at 18:47, Matt Warden wrote:
>
>> ERwin. PowerDesigner. Etc.
>>
>> However, I would caution you. The mistake most people make when
>> working on reporting is when the users say "I want a report", the
>> report developer immediately goes to "Ok, what data do we have". In
>> reality, that is irrelevant. The users need data elements A, B, and C
>> for specific reasons... so go ahead and model that in a data mart and
>> start building out the visualizations. Then you or your ETL person can
>> figure out where to get A, B, and C from.
>
> While very much +1ing Matt here, it sounds to me like you've got a bigger problem brewing in supportability - if you don't have a db of that complexity actually documented and purposefully designed in the first place then at some point it's going to fall over and you're not going to know why.
>
> Having MPIs on a mission-critical system is not fun. Not being able to explain to very, very senior people why and therefore offer any reassurance as to how long it'll take to fix, and whether it'll happen again tomorrow is even less fun.
>
> Worst case: it's organically grown spaghetti, so is the ERP system, and you are in hell.

Thanks Matt and Martin for the help.

Just to shed a little more light on the situation, the database that
I'm interacting with is part of an off the shelf avionics industry
software program. From what I can tell, it was initially designed so
that people would only be interacting from within their desktop
application, but have since allowed read only access to the underlying
database itself. However, it's pretty much a "you're on your own"
situation when working with the data in that fashion. When I contact
them for support in writing custom reports their response is to look
at the default reports and draw from them.

That said, I hate this system. If you look in any database I've built
and find a field named 'blue_widget_id', then you can bet that
anywhere you see another field with that name, it's a FK. Not in this
system. Nor do they name the same data the same thing. It might be
blue_widget_id in one table and be called inventory_id in another, yet
be the same data.

So, that's why I'm wanting to try and document this monster.

Now, some of the terms Matt threw out are new to me, so I'm off to
learn about data marts and visualizations and find out what an ETL
person is. ;)

Thanks guys!

-jeremy