varchar vs. text + constraint/triggers was: Help request to improve function performance

On Thu, 23 Apr 2009 11:00:59 +0200
Karsten Hilbert <Karsten(dot)Hilbert(at)gmx(dot)net> wrote:

> On Thu, Apr 23, 2009 at 12:02:13AM +0100, Seref Arikan wrote:
>
> > I have a set of dynamically composed objects represented in
> > Java, with string values for various attributes, which have
> > variable length. In case you have suggestions for a better type
> > for this case, it would be my pleasure to hear about them.
>
> Seref, he's suggesting you use TEXT instead of
> VARCHAR(something). In PG it's actually usually *less*
> overhead to use the unbounded text datatype (no length check
> required).
>
> Length checks mandated by business logic can be added by
> more dynamic means -- check constraints, triggers, etc which
> allow for less invasive change if needed.

Could you point us to some example of a constraint/trigger (etc...)
that is going to provide the same checking of varchar and explain
(if the code/example... doesn't make it clear) why it should be
faster or less invasive?

thanks

--
Ivan Sergio Borgonovo
http://www.webthatworks.it