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Re: I: About "Our CLUSTER implementation is pessimal" patch

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Itagaki Takahiro <itagaki(dot)takahiro(at)gmail(dot)com>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Josh Kupershmidt <schmiddy(at)gmail(dot)com>, Leonardo Francalanci <m_lists(at)yahoo(dot)it>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: I: About "Our CLUSTER implementation is pessimal" patch
Date: 2010-09-29 13:14:13
Message-ID: AANLkTimPW9Y1z=JmkyRNRO+ecLp3JrZhH_S3Sfp9PhWN@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Wed, Sep 29, 2010 at 1:12 AM, Itagaki Takahiro
<itagaki(dot)takahiro(at)gmail(dot)com> wrote:
> On Wed, Sep 29, 2010 at 1:27 PM, Alvaro Herrera
> <alvherre(at)commandprompt(dot)com> wrote:
>>> I see a consistent
>>> ~10% advantage for the sequential scan clusters.
>>
>> 10% is nothing.  I was expecting this patch would give an order of
>> magnitude of improvement or somethine like that in the worst cases of
>> the current code (highly unsorted input)
>
> Yes. It should be x10 faster than ordinary method in the worst cases.
>
> I have a performance result of pg_reorg, that performs as same as
> the patch. It shows 16 times faster than the old CLUSTER. In addition,
> it was slow if not fragmented. (So, it should not be "consistent".)
> http://reorg.projects.postgresql.org/

Can you reproduce that with this patch?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company

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