Re: Patch to implement pg_current_logfile() function

Le 03/11/2016 à 16:15, Robert Haas a écrit :
> On Wed, Oct 26, 2016 at 11:25 PM, Karl O. Pinc <kop(at)meme(dot)com> wrote:
>> What it comes down to is I don't buy the adequacy of the
>> ".csv" suffix test and think that "keeping things simple" now
>> is a recipe for future breakage, or at least significant future
>> complication and confusion when it come to processing logfile
>> content.
> Sounds like a plausible argument (although I haven't looked at the code).

Yes, the current v11 patch doesn't rely on any extension anymore,
instead the log format is now stored with the log file name.

>> My thoughts are as follows: Either you know the log format because
>> you configured the cluster or you don't. If you don't know the log
>> format having the log file is halfway useless. You can do something
>> like back it up, but you can't ever look at it's contents (in some
>> sense) without knowing what data structure you're looking at.
>>
>> Therefore pg_current_logfile() without any arguments is, in the sense
>> of any sort of automated processing of the logfile content, useless.
> Yeah, but it's not useless in general. I've certainly had cases where
> somebody gave me access to their PostgreSQL cluster to try to fix a
> problem, and I'm struggling to find the log files. Being able to ask
> the PostgreSQL cluster "where are all of the files to which you are
> logging?" sounds helpful.
>

+1

Current implementation always returns the log file in use by the logging
collector when pg_current_logfile() is called without arguments. If
stderr and csvlog are both enabled in log_destination, then it will
return the stderr log. If you need to specifically ask for the csvlog
file you can give it with as pg_current_logfile parameter.

--
Gilles Darold
Consultant PostgreSQL
http://dalibo.com - http://dalibo.org