Tom Lane wrote:
> Jan Wieck <janwieck@Yahoo.com> writes:
> > Tom Lane wrote:
> >> Hm. Perhaps the "cannot update view" test is too strict --- it's not
> >> bright enough to realize that the two rules together cover all cases,
> >> so it complains that you *might* be trying to update the view. As the
> >> code stands, you must provide an unconditional DO INSTEAD rule to
> >> implement insertion or update of a view.
>
> > Disagree.
>
> > A conditional rule splits the command into two, one with the
> > rules action and the condition added, one which is the
> > original statement plus the negated condition. So there are
> > cases left where an INSERT can happen to the view relation
> > and it's the job of this test to prevent it.
>
> Well, in that case the present code is broken, because it's going to
> spit up if any part of the rewritten query shows the view as result
> relation (cf. QueryRewrite() ... note that this logic no longer looks
> much like it did the last time you touched it ;-)). You'd have to
> convert the existing rewrite-time test into a runtime test in order to
> see whether the query actually tries to insert any tuples into the view.
Yepp.
> While that is maybe reasonable for insertions, it's totally silly
> for update and delete queries. Since the view itself can never contain
> any tuples to be updated or deleted, a runtime test that errors out
> when one attempts to update or delete such a tuple could never fire.
> I don't think that means that we shouldn't complain about an update
> or delete on a view.
>
> I think the test is best left as-is...
Since conditional rules aren't any better compared to an unconditional multi-action instead rule where
the single actions have all the different conditions, let's leave it as is and insist on one unconditional instead
rule.
Jan
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