Re: Effective IO Concurrency

From: luis(dot)roberto(at)siscobra(dot)com(dot)br
To: Ron <ronljohnsonjr(at)gmail(dot)com>
Cc: pgsql-general <pgsql-general(at)lists(dot)postgresql(dot)org>
Subject: Re: Effective IO Concurrency
Date: 2020-09-14 16:25:45
Message-ID: 330249832.8108571.1600100745617.JavaMail.zimbra@siscobra.com.br
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De: "Ron" <ronljohnsonjr(at)gmail(dot)com>
Para: "pgsql-general" <pgsql-general(at)lists(dot)postgresql(dot)org>
Enviadas: Segunda-feira, 14 de setembro de 2020 13:10:23
Assunto: Re: Effective IO Concurrency

On 9/14/20 11:03 AM, Laurenz Albe wrote:
> On Mon, 2020-09-14 at 10:39 -0300, luis(dot)roberto(at)siscobra(dot)com(dot)br wrote:
>> In PostgreSQL 13, the way of using effective_io_concurrency has changed. Until v12,
>> I used 200 for this value (using SSD drives). Using the new formula described in
>> https://www.postgresql.org/docs/13/release-13.html gives me 1176.
>> However, in the documentation https://www.postgresql.org/docs/13/runtime-config-resource.html#GUC-EFFECTIVE-IO-CONCURRENCY
>> it says that the maximum value allowed is 1000.
> Then use the value 1000...

I think he means that the formula should take that into account.

--
Angular momentum makes the world go 'round.

Exactly....

For future reference, and maybe a updated documentation:

SELECT least(round(sum(OLD / n::float)),1000) FROM generate_series(1, OLD) s(n)

I don't know how to write patches, so maybe someone can do that.

Thanks.

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