Re: User Defined Data Types

One good reason for not using them
is that you don't need to.

A second is that they can use up a lot
of space uncontrollably in the database

A third is that the attributes of a data type cannot be changed once it is in
use - and everyone makes mistakes.

A fourth is that the options for efficient data access are reduced when you start
including UDTs in the database.

A fifth is that the SQL (pl/sql) needed to address the UDTs starts to introduce obscure constructs.

If you want to translate from 'typical
OO' systems for data storage, you
might consider coding up packages
that deconstruct the OO type into
table types, and store the data as
flat tables. This allows you to have
the benefit of an OO front-end and
a high-performance back-end.

--

Jonathan Lewis
Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk

r_nandakumar_at_my-deja.com wrote in message <80q6u0$sta$1_at_nnrp1.deja.com>...
>I need feedback from application designers who have used User Defined
>Data Types in Oracle ... in particular, I would like feedback on:
>performance, indexing limitations, replication limitations, etc. .. in
>other words, is there any reason NOT to use User Defined Datatypes? The
>question is particularly relevant when one is translating models from
>typical OO systems for data storage .. if I could simply do stuff like
>the manual suggests ... e.g.
>CREATE TYPE external_person AS OBJECT (
> name VARCHAR2(30),
> phone VARCHAR2(20) );
>
Received on Tue Nov 16 1999 - 15:00:56 CST