Re: How to model searchable properties of an entity

In message <18c7b3c2.0408180730.484a40bc_at_posting.google.com>, --CELKO-- <jcelko212_at_earthlink.net> writes
>>> There are some situations where that process model fails because
>the metadata is unknown at design time, the information is not
>available to the users and so can't be encoded as the database
>structure. The example I usually quote is the library system. New
>classifications need to be added and the system has to be able to cope
>with it. <<
>
>That is a bad example; libraries have been pretty well defined and
>encoded for at least the last century. If I need a new
>classification, I have the Dewey Decimal framework to look it up if it
>already exists, or to get some open slots if it really is brand new.

I've explained Dewey's limitations in another post in this thread.

>
>>> One solution is to train all of the users up to DBA level and give
>all of them CREATE and ALTER TABLE permissions. When a user discovers
>a new attribute they just add a new field to the appropriate table.
>Having multiple DBAs working on one system is problematic but
>survivable. <<
>
>Been there; done that. Prostate cancer is also survivable.

Heh! I occasionally have to remind people that not everything is improved by being done gigitally.

>
>>> The entity-attribute-value system is an alternative but I don't
>believe it is much better, and I speak as one who has built such
>systems. You still need every user to have pretty much the same
>training as a DBA. If you can't ensure that all of your users are of
>that calibre then the system will rapidly become unworkable. <<
>
>You have to ensure that all the present users are of the highest
>calibre and then ensure that all the FUTURE users are too! If you can
>make prediction like that, then play the horses and get out of IT.

Regrettably the IT industry has retreated from me. Anyone want to hire a DBA in the UK?

>
>>> I sometimes use an e-a-v system as part of the process of designing
>a new system, but I haven't yet handed over a finished design with it
>still in place. <<
>
>If I need a "sand box" database during the design phase, I have found
>it is easy for me to write DDL on the fly. If I am gathering very raw
>data, a notebook is usually fine. I don't see EAV as even a good
>development tool.

I worked on the design of a CASE tool and an e-a-v system was part of the metadata repository.

>
>>> If you are going to have the metadata evolving as the database is
>built then there is no alternative but to have highly trained users
>with an understanding of information management. There are several
>different ways of using them but this basic requirement is pretty much
>unavoidable. <<
>
>I agree. Have you run into the "Agile Database" people yet? They
>seem to want to let the programmers design the database on the fly and
>get rid of the DBA completely.

I haven't. I'd probably stroke my beard and smile. I was there 20 years ago. I'm currently monitoring a project where the database is being designed by a java programmer. He doesn't see the point of putting business rules in the database because it's easier to code them in the application.

-- 
Bernard Peek
London, UK. DBA, Manager, Trainer & Author. Will work for money.