Re: I: About "Our CLUSTER implementation is pessimal" patch - Mailing list pgsql-hackers

From Itagaki Takahiro
Subject Re: I: About "Our CLUSTER implementation is pessimal" patch
Date
Msg-id AANLkTi=mTyE_jSL2LZm0MWB4QXesHGyKv=07mRPiS5s-@mail.gmail.com
Whole thread Raw
In response to Re: I: About "Our CLUSTER implementation is pessimal" patch  (Alvaro Herrera <alvherre@commandprompt.com>)
Responses Re: I: About "Our CLUSTER implementation is pessimal" patch  (Leonardo Francalanci <m_lists@yahoo.it>)
Re: I: About "Our CLUSTER implementation is pessimal" patch  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On Wed, Sep 29, 2010 at 1:27 PM, Alvaro Herrera
<alvherre@commandprompt.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/

--
Itagaki Takahiro


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