Re: Factoring where clauses through UNIONS take 2

Does this apply to NULLs as well?

Thank you for your extremely prompt, intelligent, and helpful replies.

Jon

On Thu, 24 Apr 2003, Tom Lane wrote:

> I said:
> > In this particular case, since the qual doesn't actually touch the
> > type-converted column, it would have been safe to push down, but the
> > planner doesn't make this test on a per-qual basis: if there are type
> > conversions anywhere in the UNION it just punts.
>
> CVS tip has now had its consciousness raised on this point ;-).  Turns
> out that it's not significantly more expensive to apply the test to
> individual vars instead of having a blanket check on the whole query,
> so I fixed it.
>
> Jonathan will still need to put the explicit casts into his view for
> use with 7.3.*, though.  He probably should do that anyway, because
> even in 7.4 a restriction on the "type" column would not get pushed
> down as desired if the literals are UNKNOWN type.
>
>             regards, tom lane
>