Обсуждение: Re: pg_xlog and standby - SOLVED

On Jan 23, 2008 11:07 PM, Greg Smith <gsmith@gregsmith.com> wrote:
> On Wed, 23 Jan 2008, Roberto Scattini wrote:
>
> > the problem that im having is that i have A LOT of
> > archive files on pg_xlog dir, and thats because the archive_command
> > keeps failing (the standby server had filled his disk with archives
> > received but not proccesed), so now, i dont know how i can remove
> > those files and start again...
>
> Under normal operation the checkpoint process will look at the number of
> already created archive files, keep around up to (2*checkpoint_segments+1)
> of them for future use, and delete the rest of them.  You never delete
> them yourself, the server will take care of that automatically once it
> gets to where it makes that decision.  If you set checkpoint_segments to
> some very high number they can end up taking many GB worth of storage,
> increasing that parameter has at least two costs associated with it (the
> other being a longer recovery time).
>

i had commented archive_command in the main server but i only made a
reload. now i made a restart and almost all files in $DATA/pg_xlog/
dir are gone, and the server works properly :D

question: all the parameters in postgresql.conf need a restart to take effect?

thanks all for your help.

--
Roberto Scattini
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On Jan 24, 2008, at 6:09 AM, Roberto Scattini wrote:

> On Jan 23, 2008 11:07 PM, Greg Smith <gsmith@gregsmith.com> wrote:
>> On Wed, 23 Jan 2008, Roberto Scattini wrote:
>>
>>> the problem that im having is that i have A LOT of
>>> archive files on pg_xlog dir, and thats because the archive_command
>>> keeps failing (the standby server had filled his disk with archives
>>> received but not proccesed), so now, i dont know how i can remove
>>> those files and start again...
>>
>> Under normal operation the checkpoint process will look at the
>> number of
>> already created archive files, keep around up to
>> (2*checkpoint_segments+1)
>> of them for future use, and delete the rest of them.  You never
>> delete
>> them yourself, the server will take care of that automatically
>> once it
>> gets to where it makes that decision.  If you set
>> checkpoint_segments to
>> some very high number they can end up taking many GB worth of
>> storage,
>> increasing that parameter has at least two costs associated with
>> it (the
>> other being a longer recovery time).
>>
>
> i had commented archive_command in the main server but i only made a
> reload. now i made a restart and almost all files in $DATA/pg_xlog/
> dir are gone, and the server works properly :D
>
> question: all the parameters in postgresql.conf need a restart to
> take effect?
>
> thanks all for your help.

Ah, yes, that's a gotcha with the archive_command, at least I know it
was a gotme at one point :)  To disable archiving, set
archive_command="", commenting it out won't change it.  The only
config paramaters that require a restart to take effect are those
that are specifically noted as such in the manual section on server
configuration.  However, commenting a config is not necessarily
equivalent to disabling something.

Erik Jones

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erik@myemma.com
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On Thu, 24 Jan 2008, Erik Jones wrote:

> To disable archiving, set archive_command="", commenting it out won't
> change it...However, commenting a config is not necessarily equivalent
> to disabling something.

This is actually a problem that is corrected in the upcoming 8.3 release.
From those release notes:

"Commenting out a parameter in postgresql.conf now causes it to revert to
its default value.  [In 8.2 and earlier releases] commenting out an entry
left the parameter's value unchanged until the next server restart."

This is probably why Roberto didn't see the expected behavior until a
server restart.

--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD

On Jan 24, 2008 4:30 PM, Greg Smith <gsmith@gregsmith.com> wrote:
> On Thu, 24 Jan 2008, Erik Jones wrote:
>
> > To disable archiving, set archive_command="", commenting it out won't
> > change it...However, commenting a config is not necessarily equivalent
> > to disabling something.
>
> This is actually a problem that is corrected in the upcoming 8.3 release.
> From those release notes:
>
> "Commenting out a parameter in postgresql.conf now causes it to revert to
> its default value.  [In 8.2 and earlier releases] commenting out an entry
> left the parameter's value unchanged until the next server restart."
>
> This is probably why Roberto didn't see the expected behavior until a
> server restart.
>

in fact, googling for the problem i found those release notes that led
me to think that the restart was necessary...
:D

--
Roberto Scattini
 ___     _
 ))_) __ )L __
((__)(('(( ((_)