Re: IMMUTABLE columns in tables?

avbidder(at)fortytwo(dot)ch (Adrian von Bidder) writes:
> Heyho!
>
> (Ok, seems to be feature wish day ...)
>
> I was wondering if others would find an IMMUTABLE (or whatever) column
> constraint useful as well. Semantics would (obviously?) be to disallow
> changing the value of this column after insert.
>
> I realize that this is possible via triggers, and with the recent
> possibility of having triggers fire only on changes to certain columns it's
> even (presumably) not much runtime overhead, but creating triggers is very
> verbose and doesn't make the db schema very readable.

I'd like that feature, and I don't think it takes too much arguing to
get to the point that a declarative "IMMUTABLE" control is rather less
opaque than someone saying "oh, you could just create a trigger
running PL/LOLCODE to do that!"

I thought that this was on the Todo list, but I don't see it.
<http://wiki.postgresql.org/wiki/Todo>

If you're keen on getting it onto the ToDo list, the argumentation
process would be made easier if the material about this included
answers to a couple more questions:
- What do other databases use as syntax for this?
- Does SQL standard have anything to say about how this sort
of thing ought to be declared?
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