[thelist] mapping out an oracle database

[Martin Burns]

On 25 Feb 2010, at 18:47, Matt Warden wrote:

> On Thu, Feb 25, 2010 at 10:47 AM, Jeremy Weiss wrote:
>> Lately I've been having to write a good deal of custom reports for a
>> ERP-ish system we use. However, I'm consistently having problems
>> trying to trace a path from one table to another. What I'd like to do
>> (I think) is chart out the system and put together a large diagram
>> showing which tables are related and by what fields. But, this
>> database is 680+ tables large so I'd rather not do it by hand. Is
>> there a script/program out there that could analyze all the tables and
>> put something like this together for me?
> 
> 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. 

Cheers
Martin
(who has experience of this at the day job client)

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