Re: Enable logging requires restart

On 24 September 2010 16:52, Andrew Dunstan <andrew@dunslane.net> wrote:
>
>
> On 09/24/2010 08:22 AM, Thom Brown wrote:
>>
>> On 24 September 2010 13:17, Robert Haas<robertmhaas@gmail.com>  wrote:
>>>
>>> On Fri, Sep 24, 2010 at 4:33 AM, Thom Brown<thom@linux.com>  wrote:
>>>>
>>>> At the moment, to enable logging, a service restart is required.  Is
>>>> there any way to remove this requirement or is there a fundamental
>>>> reason why it must always be like that?
>>>
>>> Are you speaking of the logging_collector GUC?  I think the difficulty
>>> is - if you wanted to turn this on without a restart, how would you
>>> get the collector's stdin to be each backend's stdout/stderr?  I don't
>>> see any way to do it, actually.
>>
>> This is probably blasphemy, but "off" would log to a symbolic link
>> pointing to /dev/null, which is repointed to a log_file if reloaded
>> with "on"?
>
> No, off simply means we aren't collecting the log, not that we aren't
> producing any. All the buildfarm tests run without using the logging
> collector, but they DO produce logs :-)
>
> What's the use case for making it settable on the fly? I can't see that this
> is worth the probably quite large amount of coding that would be required.

A very busy server you can't afford to have down.  There's a server at
work which serves a lot of clients and it's always busy.  An attempt
to restart would be waiting for running queries to finish while
denying new connections, and during this time, web applications
dependent on it are non-functional.  I noticed we weren't logging on
that server and needed to enable it.  In this case I've changed the
config to the required setting, but won't take effect until one of
those rare times when we restart the daemon or server.  But the
problem now is, in the meantime, if something goes wrong, I won't be
able to see exactly what.

--
Thom Brown
Twitter: @darkixion
IRC (freenode): dark_ixion
Registered Linux user: #516935