Re: Another documentation issue

From: Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at>
To: Igor Korot <ikorot01(at)gmail(dot)com>, "pgsql-generallists(dot)postgresql(dot)org" <pgsql-general(at)lists(dot)postgresql(dot)org>
Subject: Re: Another documentation issue
Date: 2025-04-23 07:16:23
Message-ID: 03763b6b43cfd8a7194c2fb06452178db4256494.camel@cybertec.at
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On Wed, 2025-04-23 at 00:21 -0500, Igor Korot wrote:
> On the page https://www.postgresql.org/docs/current/runtime-config-query.html#GUC-SEQ-PAGE-COST
>
> it is only given the default value of this parameter.
>
> No min/max values are provided..
>
> The same can be sad about
> https://www.postgresql.org/docs/current/runtime-config-query.html#GUC-RANDOM-PAGE-COST

Sad. But you can interpret it as "there is no maximum". The actual maximum is DBL_MAX,
the biggest double precision value that your system can handle, and may depend on your
architecture.

> However, this page
> https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-EFFECTIVE-IO-CONCURRENCY
> describes both default and mn/max, however t s says:
>
> [quote]
> The default is 1 on supported systems, otherwise 0
> [/quote]]
>
> No explanation of what is "supported system" is given...
>
> And the same can be said about
> https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-MAINTENANCE-IO-CONCURRENCY.

According to the source, it is "systems that have posix_fadvise()". We could document that,
but I don't know if it would help many people. I am not sure how easy and feasible it is
to research which versions of which operating systems qualify.

Yours,
Laurenz Albe

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