From: Marcos Ortiz Valmaseda <mlortiz@uci.cu>
To: Peter van Hardenberg <pvh@pvh.ca>
Cc: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Josh Berkus <josh@agliodbs.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: random_page_cost = 2.0 on Heroku Postgres
Date: Wed, 08 Feb 2012 21:35:19 -0430
Message-ID: <4F3329DF.2060805@uci.cu> (raw)
In-Reply-To: <CAAcg=kXzU8BDySsJKuBPLXRn7opoPX33fMcxNL33GCZgOF98rQ@mail.gmail.com>
References: <CAAcg=kWsjAXRNt0sSjsF-Ft+NfZi30Owa=-PGvghSJ6A0jeVYQ@mail.gmail.com>
<4F331866.7070401@agliodbs.com>
<CAOR=d=2QNts+9tS6SYcgKhSM56MbJPR2Js=B9YWfGehUVR+i+Q@mail.gmail.com>
<CAAcg=kXzU8BDySsJKuBPLXRn7opoPX33fMcxNL33GCZgOF98rQ@mail.gmail.com>
On 08/02/12 21:15, Peter van Hardenberg wrote:
> Having read the thread, I don't really see how I could study what a
> more principled value would be.
>
> That said, I have access to a very large fleet in which to can collect
> data so I'm all ears for suggestions about how to measure and would
> gladly share the results with the list.
>
> Peter
>
> On Wed, Feb 8, 2012 at 5:39 PM, Scott Marlowe<scott.marlowe@gmail.com> wrote:
>> On Wed, Feb 8, 2012 at 5:50 PM, Josh Berkus<josh@agliodbs.com> wrote:
>>> On 2/7/12 4:59 PM, Peter van Hardenberg wrote:
>>>> Per the thread from last month, I've updated the default
>>>> random_page_cost on Heroku Postgres to reduce the expected cost of a
>>>> random_page on all new databases.
>>> This is because Heroku uses AWS storage, which has fast seeks but poor
>>> throughput compared to internal disk on a standard system, BTW.
>> Also judging by the other thread, it might be something to stop closer
>> to 1.2 to 1.4 or something.
>>
>> --
>> Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
>> To make changes to your subscription:
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>
>
You can execute several queries with the three different values provided
by Scott and Josh.
- SET random_page_cost = 2.0
First execution of the queries with EXPLAIN ANALYZE
- SET random_page_cost = 1.4
Second execution of the queries with EXPLAIN ANALYZE
- SET random_page_cost = 1.2
Second execution of the queries with EXPLAIN ANALYZE
And then, you can compare the pattern behind these queries executions
Regards,
--
Marcos Luis OrtÃz Valmaseda
Sr. Software Engineer (UCI)
http://marcosluis2186.posterous.comhttp://www.linkedin.com/in/marcosluis2186
Twitter: @marcosluis2186
Fin a la injusticia, LIBERTAD AHORA A NUESTROS CINCO COMPATRIOTAS QUE SE ENCUENTRAN INJUSTAMENTE EN PRISIONES DE LOS EEUU!
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To: pgsql-performance@postgresql.org
Cc: mlortiz@uci.cu, pvh@pvh.ca, scott.marlowe@gmail.com, josh@agliodbs.com
Subject: Re: random_page_cost = 2.0 on Heroku Postgres
In-Reply-To: <4F3329DF.2060805@uci.cu>
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