Re: How to union tables and have a field with UNIQUE constraint?

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От Stephan Szabo
Тема Re: How to union tables and have a field with UNIQUE constraint?
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Msg-id 20020103134126.Y14151-100000@megazone23.bigpanda.com
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Ответ на Re: How to union tables and have a field with UNIQUE constraint?  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: How to union tables and have a field with UNIQUE constraint?  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Thu, 3 Jan 2002, Tom Lane wrote:

> Stephan Szabo <sszabo@megazone23.bigpanda.com> writes:
> > I assume you want to reference id, so you'd need to do something like:
>
> > CREATE UNIQUE INDEX t_id_key ON t(id);
>
> Do we allow that (defining an index on a view)?  [ tries it ]
> Apparently so :-(
>
> I would argue that this should be disallowed, since it does not do
> anything useful and can only mislead people into thinking that it
> has some effect.

Yeah, I was surprised that it let me do it as well.

> > This is a hacky sort of way to do it (we allow you to make the internal
> > form that a unique constraint has via create index even on views which
> > I don't believe would ever be used :( ) and may not continue working
> > forever.
>
> Since triggers on a view won't do anything either, I don't see how one
> could expect REFERENCES to a view to work.  The system ought to reject
> all this stuff as unimplemented.

I think that the insert/update on the fk table will work, but yeah, the
parts on the pk table won't, so that's no good.  I wouldn't want to
bother for 7.2, but putting in something to make it so you can't reference
a view is probably a good idea, at least until we can work out a way
to make constraints on views work.



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