| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Greg Stark <gsstark(at)mit(dot)edu> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, Krowa Krowax <krowa333(at)gmail(dot)com>, pgsql-admin(at)postgresql(dot)org |
| Subject: | Re: Vacuum Full - stops responding(?) |
| Date: | 2009-10-21 03:03:40 |
| Message-ID: | 20091021030340.GC29592@alvh.no-ip.org |
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| Lists: | pgsql-admin |
Greg Stark escribió:
> On Mon, Oct 19, 2009 at 8:56 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Greg Stark <gsstark(at)mit(dot)edu> writes:
> >> The run-time of CLUSTER doesn't vary very much based on whether the
> >> data is already in index order or not. The number of passes only grows
> >> like log(n) of the size of your data and if you set
> >> maintenance_work_mem large enough (somewhere around 100MB-1GB) the
> >> constants are small enough that you're unlikely to even outgrow a
> >> single pass (plus a final merge though)
> >
> > Uh ... what? It's not based on the sort code, unless someone rewrote it
> > since I looked last. It's an index scan and will definitely depend on
> > the index ordering.
>
> Er, uh, of course. I wonder what I was thinking.
Your patched version of course.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
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