Subject: Re: vacuum_cost_limit doc description patch
To: David Rowley <david.rowley@2ndquadrant.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
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From: =?UTF-8?Q?Mart=c3=adn_Marqu=c3=a9s?= <martin.marques@2ndquadrant.com>
Message-ID: <afe7730c-4ba7-3f9f-5184-1debadd18af3@2ndquadrant.com>
Date: Fri, 13 Apr 2018 09:56:18 -0300
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El 11/04/18 a las 02:04, David Rowley escribió:
> On 11 April 2018 at 09:13, Martín Marqués <martin.marques@gmail.com> wrote:
>> This is a patch to add some further description, plus the upper and
>> lower limits it has.
> 
> Hi,
> 
> +         for vacuum_cost_delay. The parameter can take a value
> between 1 and 10000.
> 
> vacuum_cost_delay should be in <varname> tags.
> 
> +1 to mentioning that we sleep for vacuum_cost_delay, but I just don't
> see many other GUCs with mention of their supported range.

Thanks David for having a look.

New version attached with the missing <varname> tags.

> effective_io_concurrency mentions the range it supports, but this
> happens to depend on USE_POSIX_FADVISE, which if undefined the maximum
> setting is 0, which means the docs are wrong in some cases on that.
> 
> vacuum_cost_limit seems fairly fixed at 0-10000 with no compile-time
> conditions, so perhaps it's okay, providing we remember and update the
> docs if that ever changes.

I'm also adding a second patch over the config.sgml doc to fix what I
believe is a misguidance in the minimum resolution time modern systems have.

The patch just changes *many* for *some* systems which have a minimum
resolution time of 10 milliseconds.

-- 
Martín Marqués                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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