| From: | Greg Stark <gsstark(at)mit(dot)edu> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | 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: | 2009-10-20 04:02:57 |
| Message-ID: | 407d949e0910192102x49724a0akad197260b1aeae79@mail.gmail.com |
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| Lists: | pgsql-admin |
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.
Sorry
--
greg
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