Re: Bitmap index scans use of filters on available columns

On Fri, Nov 6, 2015 at 10:28 AM, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp> wrote:
>
> Hello,
>
> At Fri, 6 Nov 2015 09:49:30 +0530, Amit Kapila <amit.kapila16@gmail.com> wrote in <CAA4eK1L_5T-UYsQeMOrX54g3QeXGhhAk5YFmzZqu5MidzxzkRg@mail.gmail.com>
> > Apart from other problems discussed, I think it could also lead to
> > a performance penality for the cases when the qual condition is
> > costly as evaluating such a qual against lot of dead rows would be a
> > time consuming operation.  I am not sure, but I think some of the
> > other well know databases might not have any such problems as
> > they store visibility info inside index due to which they don't need to
> > fetch the heap tuple for evaluating such quals.
>
> I was junst thinking of the same thing. Can we estimate the
> degree of the expected penalty using heap statistics? Of couse
> not so accurate though.
>