| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | jd <jd(at)commandprompt(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Better estimates of index correlation |
| Date: | 2011-03-14 14:25:46 |
| Message-ID: | 1300112623-sup-7438@alvh.no-ip.org |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Excerpts from Robert Haas's message of lun mar 14 11:18:24 -0300 2011:
> On Mon, Mar 14, 2011 at 10:09 AM, Alvaro Herrera
> <alvherre(at)commandprompt(dot)com> wrote:
> > It sure would be nice to be able to do it only during the last scan.
>
> Does it really matter? What Tom was describing sounded embarassingly cheap.
Well, you only do multiple passes for tables that are really large, so
it's precisely there that you want to save the extra overhead of having
to do it multiple times.
As Heikki says, maybe this wouldn't be an issue at all if we can do it
during ANALYZE instead, but I don't know if that works.
--
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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