From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
---|---|
To: | Justin Pryzby <pryzby(at)telsasoft(dot)com> |
Cc: | James Coleman <jtc331(at)gmail(dot)com>, David Steele <david(at)pgmasters(dot)net>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Alexey Bashtanov <bashtanov(at)imap(dot)cc>, Emre Hasegeli <emre(at)hasegeli(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: improve transparency of bitmap-only heap scans |
Date: | 2020-03-24 06:13:32 |
Message-ID: | CAA4eK1JbBRqi=1D89+8UvjqdmUnJbbaizUtgWz3b2zRsFYf2TA@mail.gmail.com |
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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
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