Re: Help, my developers are killing me with varchar2(4000)
- From: Tim X <timx@xxxxxxxxxxxxxxx>
- Date: Tue, 29 Jul 2008 18:14:02 +1000
RogBaker@xxxxxxxxx writes:
I have a developer that created some tables in a development instnace
and wants me to promote them to QA. I took a look at them, and nearly
every column is varchar2(4000). I am pretty sure this is overkill for
most of them. I know it takes up as much room as the data, but I just
don't like this design philosophy. Does anyone have any references/
urls saying this is a bad idea to design tables like this? It has been
my experience that you get bad data by allowing columns to contain
more data then what it should really hold.
Thanks in advance,
OMG - are som eof our developers working for you as well?
I have this arguement regularly, particularly with web developers for
some reason. I'll be there are no check, fk or any other referenctial
integrity constraints in there as well!
I think part of the problem here is that many, particularly young and
often web oriented developers just use the database as a 'bit
bucket'. We had exactly this issue recently. Not only were all the
fields varchar2(400) (including ones used to store dates, timestamps,
and numbers - even unnatural primary keys that used sequences to
generate the unique key) the tables were called things like bens_data
where Ben is one of the developers. Worse still, all the logic
reagarding the data relationships and constraints was handled in the
client app code (more often than not java/jsp),
I think essentially, it is a combination of laziness (can't be bothered
actually doing any formal analysis and data modeling) and ignorance
(don't even understand when I try to explain why its bad design).
I regularly try to explain the benefits of using the facilities of the
database to assist in managing your data e.g. don't have to replicate
the logic in every client app and therefore don't have problems in
keeping things consistent between apps, providing valuable information
for the poor suckers that end up having to maintain the apps etc. All I
get back is that their way is more flexible and quicker. My way is
slower and harder to modify. Of course, they don't consider
maintenance.
A big part of the problem is lack of experience. For some reason, there
is this growing belief in some management quarters that these young
recent graduates, who are half the cost of more experienced developers,
are doing excellent work - I mean, seew snazy that web page looks. Of
course, when they realise the app is becoming nearly impossible to
maintain, the original developer has moved on and so has the
manager. Some new manager and new recent grad is responsible. they end
up bitching about how bad the previous lot were and then go about
re-implementing the app because its too hard to maintain. Unfortunately,
they just do the same thing all over again and the whole process starts
another cycle.
All I can suggest is to keep pushing your case and don't get too
frustrated when you can't get any support for your arguments. If your
really really into frustration and pain, start talking about the
benefits of developers using things like dbms_application_info and
providing some help to the DBAs who keep getting hassled to solve
performance problems etc. I'm not a DBA BTW.
Tim
--
tcross (at) rapttech dot com dot au
.
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