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* Re: Another documentation issue
@ 2025-04-23 07:16 Laurenz Albe <[email protected]>
2025-04-23 09:14 ` Re: Another documentation issue Daniel Gustafsson <[email protected]>
2025-04-24 05:26 ` Re: Another documentation issue Igor Korot <[email protected]>
0 siblings, 2 replies; 10+ messages in thread
From: Laurenz Albe @ 2025-04-23 07:16 UTC (permalink / raw)
To: Igor Korot <[email protected]>; pgsql-generallists.postgresql.org <[email protected]>
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
^ permalink raw reply [nested|flat] 10+ messages in thread
* Re: Another documentation issue
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
@ 2025-04-23 09:14 ` Daniel Gustafsson <[email protected]>
2025-04-23 18:28 ` Re: Another documentation issue Tom Lane <[email protected]>
2025-04-24 08:02 ` Re: Another documentation issue Peter Eisentraut <[email protected]>
1 sibling, 2 replies; 10+ messages in thread
From: Daniel Gustafsson @ 2025-04-23 09:14 UTC (permalink / raw)
To: Laurenz Albe <[email protected]>; +Cc: Igor Korot <[email protected]>; pgsql-generallists.postgresql.org <[email protected]>
> On 23 Apr 2025, at 09:16, Laurenz Albe <[email protected]> wrote:
> On Wed, 2025-04-23 at 00:21 -0500, Igor Korot wrote:
>> 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.
From memory it's supported on FreeBSD, NetBSD and Linux with Windows, macOS and
OpenBSD not supporting it. Assuming I'm not completely wrong (a 1 minute
search shows it's in the ballpark) we could perhaps add something like
"Unsupported platforms include (but isn't limited to) Windows and macOS" which
would provide a bit more clarity.
--
Daniel Gustafsson
^ permalink raw reply [nested|flat] 10+ messages in thread
* Re: Another documentation issue
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
2025-04-23 09:14 ` Re: Another documentation issue Daniel Gustafsson <[email protected]>
@ 2025-04-23 18:28 ` Tom Lane <[email protected]>
2025-04-23 18:32 ` Re: Another documentation issue Igor Korot <[email protected]>
1 sibling, 1 reply; 10+ messages in thread
From: Tom Lane @ 2025-04-23 18:28 UTC (permalink / raw)
To: Daniel Gustafsson <[email protected]>; +Cc: Laurenz Albe <[email protected]>; Igor Korot <[email protected]>; pgsql-generallists.postgresql.org <[email protected]>
Daniel Gustafsson <[email protected]> writes:
>> On 23 Apr 2025, at 09:16, Laurenz Albe <[email protected]> wrote:
>> On Wed, 2025-04-23 at 00:21 -0500, Igor Korot wrote:
>>> No explanation of what is "supported system" is given...
>> 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.
>> From memory it's supported on FreeBSD, NetBSD and Linux with Windows, macOS and
> OpenBSD not supporting it. Assuming I'm not completely wrong (a 1 minute
> search shows it's in the ballpark) we could perhaps add something like
> "Unsupported platforms include (but isn't limited to) Windows and macOS" which
> would provide a bit more clarity.
If we do anything about this, I'd just say "systems that have
posix_fadvise()". If we write something more specific it's likely to
become obsolete, and it doesn't seem to me that it's hard for someone
to research "does my box have posix_fadvise()?".
regards, tom lane
^ permalink raw reply [nested|flat] 10+ messages in thread
* Re: Another documentation issue
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
2025-04-23 09:14 ` Re: Another documentation issue Daniel Gustafsson <[email protected]>
2025-04-23 18:28 ` Re: Another documentation issue Tom Lane <[email protected]>
@ 2025-04-23 18:32 ` Igor Korot <[email protected]>
2025-04-23 18:40 ` Re: Another documentation issue Tom Lane <[email protected]>
0 siblings, 1 reply; 10+ messages in thread
From: Igor Korot @ 2025-04-23 18:32 UTC (permalink / raw)
To: Tom Lane <[email protected]>; +Cc: Daniel Gustafsson <[email protected]>; Laurenz Albe <[email protected]>; pgsql-generallists.postgresql.org <[email protected]>
Hi, Tom,
On Wed, Apr 23, 2025 at 1:28 PM Tom Lane <[email protected]> wrote:
> Daniel Gustafsson <[email protected]> writes:
> >> On 23 Apr 2025, at 09:16, Laurenz Albe <[email protected]>
> wrote:
> >> On Wed, 2025-04-23 at 00:21 -0500, Igor Korot wrote:
> >>> No explanation of what is "supported system" is given...
>
> >> 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.
>
> >> From memory it's supported on FreeBSD, NetBSD and Linux with Windows,
> macOS and
> > OpenBSD not supporting it. Assuming I'm not completely wrong (a 1 minute
> > search shows it's in the ballpark) we could perhaps add something like
> > "Unsupported platforms include (but isn't limited to) Windows and macOS"
> which
> > would provide a bit more clarity.
>
> If we do anything about this, I'd just say "systems that have
> posix_fadvise()". If we write something more specific it's likely to
> become obsolete, and it doesn't seem to me that it's hard for someone
> to research "does my box have posix_fadvise()?
Imagine a person that wants to write a program which will cover creating
the table space.
Such person needs to cover the appropriate fields with possible values.
Is there a #define such person should check to cover the appropriate values?
Thank you?
".
>
> regards, tom lane
>
^ permalink raw reply [nested|flat] 10+ messages in thread
* Re: Another documentation issue
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
2025-04-23 09:14 ` Re: Another documentation issue Daniel Gustafsson <[email protected]>
2025-04-23 18:28 ` Re: Another documentation issue Tom Lane <[email protected]>
2025-04-23 18:32 ` Re: Another documentation issue Igor Korot <[email protected]>
@ 2025-04-23 18:40 ` Tom Lane <[email protected]>
2025-04-23 20:15 ` Re: Another documentation issue Igor Korot <[email protected]>
2025-04-24 05:09 ` Re: Another documentation issue Igor Korot <[email protected]>
0 siblings, 2 replies; 10+ messages in thread
From: Tom Lane @ 2025-04-23 18:40 UTC (permalink / raw)
To: Igor Korot <[email protected]>; +Cc: Daniel Gustafsson <[email protected]>; Laurenz Albe <[email protected]>; pgsql-generallists.postgresql.org <[email protected]>
Igor Korot <[email protected]> writes:
> On Wed, Apr 23, 2025 at 1:28 PM Tom Lane <[email protected]> wrote:
>> If we do anything about this, I'd just say "systems that have
>> posix_fadvise()". If we write something more specific it's likely to
>> become obsolete, and it doesn't seem to me that it's hard for someone
>> to research "does my box have posix_fadvise()?
> Imagine a person that wants to write a program which will cover creating
> the table space.
> Such person needs to cover the appropriate fields with possible values.
> Is there a #define such person should check to cover the appropriate values?
HAVE_POSIX_FADVISE. Seems to me it'd be way easier to find that
from documentation that mentions posix_fadvise than from documentation
that says "it works on systems X, Y, Z".
regards, tom lane
^ permalink raw reply [nested|flat] 10+ messages in thread
* Re: Another documentation issue
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
2025-04-23 09:14 ` Re: Another documentation issue Daniel Gustafsson <[email protected]>
2025-04-23 18:28 ` Re: Another documentation issue Tom Lane <[email protected]>
2025-04-23 18:32 ` Re: Another documentation issue Igor Korot <[email protected]>
2025-04-23 18:40 ` Re: Another documentation issue Tom Lane <[email protected]>
@ 2025-04-23 20:15 ` Igor Korot <[email protected]>
1 sibling, 0 replies; 10+ messages in thread
From: Igor Korot @ 2025-04-23 20:15 UTC (permalink / raw)
To: Tom Lane <[email protected]>; +Cc: Daniel Gustafsson <[email protected]>; Laurenz Albe <[email protected]>; pgsql-generallists.postgresql.org <[email protected]>
Tom,
On Wed, Apr 23, 2025 at 1:40 PM Tom Lane <[email protected]> wrote:
> Igor Korot <[email protected]> writes:
> > On Wed, Apr 23, 2025 at 1:28 PM Tom Lane <[email protected]> wrote:
> >> If we do anything about this, I'd just say "systems that have
> >> posix_fadvise()". If we write something more specific it's likely to
> >> become obsolete, and it doesn't seem to me that it's hard for someone
> >> to research "does my box have posix_fadvise()?
>
> > Imagine a person that wants to write a program which will cover creating
> > the table space.
> > Such person needs to cover the appropriate fields with possible values.
> > Is there a #define such person should check to cover the appropriate
> values?
>
> HAVE_POSIX_FADVISE. Seems to me it'd be way easier to find that
> from documentation that mentions posix_fadvise than from documentation
> that says "it works on systems X, Y, Z".
Agreed.
Hopefully someone can put this in…
Thx.
>
> regards, tom lane
>
^ permalink raw reply [nested|flat] 10+ messages in thread
* Re: Another documentation issue
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
2025-04-23 09:14 ` Re: Another documentation issue Daniel Gustafsson <[email protected]>
2025-04-23 18:28 ` Re: Another documentation issue Tom Lane <[email protected]>
2025-04-23 18:32 ` Re: Another documentation issue Igor Korot <[email protected]>
2025-04-23 18:40 ` Re: Another documentation issue Tom Lane <[email protected]>
@ 2025-04-24 05:09 ` Igor Korot <[email protected]>
2025-04-24 05:23 ` Re: Another documentation issue David G. Johnston <[email protected]>
1 sibling, 1 reply; 10+ messages in thread
From: Igor Korot @ 2025-04-24 05:09 UTC (permalink / raw)
To: Tom Lane <[email protected]>; +Cc: Daniel Gustafsson <[email protected]>; Laurenz Albe <[email protected]>; pgsql-generallists.postgresql.org <[email protected]>
Tom,
On Wed, Apr 23, 2025 at 1:40 PM Tom Lane <[email protected]> wrote:
>
> Igor Korot <[email protected]> writes:
> > On Wed, Apr 23, 2025 at 1:28 PM Tom Lane <[email protected]> wrote:
> >> If we do anything about this, I'd just say "systems that have
> >> posix_fadvise()". If we write something more specific it's likely to
> >> become obsolete, and it doesn't seem to me that it's hard for someone
> >> to research "does my box have posix_fadvise()?
>
> > Imagine a person that wants to write a program which will cover creating
> > the table space.
> > Such person needs to cover the appropriate fields with possible values.
> > Is there a #define such person should check to cover the appropriate values?
>
> HAVE_POSIX_FADVISE. Seems to me it'd be way easier to find that
> from documentation that mentions posix_fadvise than from documentation
> that says "it works on systems X, Y, Z".
Most of the time the client and server are located on different machines.
So there is no way to identify what server is supporting.
How do you handle sch situation from the client POV?
Thank you.
>
> regards, tom lane
^ permalink raw reply [nested|flat] 10+ messages in thread
* Re: Another documentation issue
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
2025-04-23 09:14 ` Re: Another documentation issue Daniel Gustafsson <[email protected]>
2025-04-23 18:28 ` Re: Another documentation issue Tom Lane <[email protected]>
2025-04-23 18:32 ` Re: Another documentation issue Igor Korot <[email protected]>
2025-04-23 18:40 ` Re: Another documentation issue Tom Lane <[email protected]>
2025-04-24 05:09 ` Re: Another documentation issue Igor Korot <[email protected]>
@ 2025-04-24 05:23 ` David G. Johnston <[email protected]>
0 siblings, 0 replies; 10+ messages in thread
From: David G. Johnston @ 2025-04-24 05:23 UTC (permalink / raw)
To: Igor Korot <[email protected]>; +Cc: Tom Lane <[email protected]>; Daniel Gustafsson <[email protected]>; Laurenz Albe <[email protected]>; pgsql-generallists.postgresql.org <[email protected]>
On Wednesday, April 23, 2025, Igor Korot <[email protected]> wrote:
>
> How do you handle sch situation from the client POV?
>
Get the current value. If it’s non-zero the system definitely supports
it. If it’s zero it probably doesn’t. But give the user an option to
specify a value anyway just in case. If they try and it errors, it doesn’t
support it.
David J.
^ permalink raw reply [nested|flat] 10+ messages in thread
* Re: Another documentation issue
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
2025-04-23 09:14 ` Re: Another documentation issue Daniel Gustafsson <[email protected]>
@ 2025-04-24 08:02 ` Peter Eisentraut <[email protected]>
1 sibling, 0 replies; 10+ messages in thread
From: Peter Eisentraut @ 2025-04-24 08:02 UTC (permalink / raw)
To: Daniel Gustafsson <[email protected]>; Laurenz Albe <[email protected]>; +Cc: Igor Korot <[email protected]>; pgsql-generallists.postgresql.org <[email protected]>
On 23.04.25 11:14, Daniel Gustafsson wrote:
>> On 23 Apr 2025, at 09:16, Laurenz Albe <[email protected]> wrote:
>> On Wed, 2025-04-23 at 00:21 -0500, Igor Korot wrote:
>
>>> 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.
>
> From memory it's supported on FreeBSD, NetBSD and Linux with Windows, macOS and
> OpenBSD not supporting it. Assuming I'm not completely wrong (a 1 minute
> search shows it's in the ballpark) we could perhaps add something like
> "Unsupported platforms include (but isn't limited to) Windows and macOS" which
> would provide a bit more clarity.
Note that PG18 supports prefetching on macOS without posix_fadvise(),
and we changed some of the documentation text to not mention
posix_fadvise() anymore. Also, some of the text and the defaults have
changed because of the async IO feature set. Maybe see if the text in
master provides the information you need.
^ permalink raw reply [nested|flat] 10+ messages in thread
* Re: Another documentation issue
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
@ 2025-04-24 05:26 ` Igor Korot <[email protected]>
1 sibling, 0 replies; 10+ messages in thread
From: Igor Korot @ 2025-04-24 05:26 UTC (permalink / raw)
To: Laurenz Albe <[email protected]>; +Cc: pgsql-generallists.postgresql.org <[email protected]>
Hi, Laurenz,
On Wed, Apr 23, 2025 at 2:16 AM Laurenz Albe <[email protected]> wrote:
>
> 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.
So if I want to execute it from the client code (whether ODBC based or
libpq based),
how do I handle it?
Because most of the time client and server are located on different machines...
Thank you.
>
> > 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
^ permalink raw reply [nested|flat] 10+ messages in thread
end of thread, other threads:[~2025-04-24 08:02 UTC | newest]
Thread overview: 10+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2025-04-23 07:16 Re: Another documentation issue Laurenz Albe <[email protected]>
2025-04-23 09:14 ` Daniel Gustafsson <[email protected]>
2025-04-23 18:28 ` Tom Lane <[email protected]>
2025-04-23 18:32 ` Igor Korot <[email protected]>
2025-04-23 18:40 ` Tom Lane <[email protected]>
2025-04-23 20:15 ` Igor Korot <[email protected]>
2025-04-24 05:09 ` Igor Korot <[email protected]>
2025-04-24 05:23 ` David G. Johnston <[email protected]>
2025-04-24 08:02 ` Peter Eisentraut <[email protected]>
2025-04-24 05:26 ` Igor Korot <[email protected]>
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