Re: improve transparency of bitmap-only heap scans

On Tue, Mar 24, 2020 at 11:36 AM Justin Pryzby <pryzby(at)telsasoft(dot)com> wrote:
>
> On Tue, Mar 24, 2020 at 10:54:05AM +0530, Amit Kapila wrote:
> > On Fri, Mar 20, 2020 at 7:09 AM James Coleman <jtc331(at)gmail(dot)com> wrote:
> > >
> > > Awesome, thanks for confirming with an actual plan.
> > >
> > > > I don't think it matters in nontext mode, but at least in text mode, I think
> > > > maybe the Unfetched blocks should be output after the exact and lossy blocks,
> > > > in case someone is parsing it, and because bitmap-only is a relatively new
> > > > feature. Its output is probably less common than exact/lossy.
> > >
> > > I tweaked that (and a comment that didn't reference the change); see attached.
> > >
> >
> > Few comments:
> > 1.
> > -
> > - if (tbmres->ntuples >= 0)
> > + else if (tbmres->ntuples >= 0)
> > node->exact_pages++;
> >
> > How is this change related to this patch?
>
> Previously, a page was either "exact" or "lossy".
> Now it's one of exact/lossy/skipped.
>

Okay, that makes sense.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com