| From: | Greg Stark <stark(at)mit(dot)edu> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Bruce Momjian <bruce(at)momjian(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: COUNT(*) and index-only scans |
| Date: | 2011-10-11 04:45:54 |
| Message-ID: | CAM-w4HOscbrS1kyjO0H7BnPozn1thrpa=h6xmxUTXX-aA9V8eA@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Mon, Oct 10, 2011 at 9:17 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> My intention was to allow it to consider any covering index. You're
> thinking about the cost estimate, which is really entirely different.
>
Is there any reason to consider more than one? I would have expected
the narrowest one to be the best choice. There's something to be said
for using the same index consistently but we already have that problem
and make no attempt to do that. And partial indexes might be better
but then we would already be considering them if their constraints are
satisfied.
--
greg
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Kevin Grittner | 2011-10-11 04:48:04 | Re: COUNT(*) and index-only scans |
| Previous Message | Tom Lane | 2011-10-11 04:19:55 | Re: index-only scans |