Re: WIP: Separate log file for extension

Magnus Hagander <magnus(at)hagander(dot)net> wrote:

> > On Fri, Aug 25, 2017 at 12:12 AM, Antonin Houska <ah(at)cybertec(dot)at> wrote:

>
> I like this idea in general.
>
> Then it's supposed to change some of its attributes
>
> > adjust_log_stream_attr(&stream->filename, "my_extension.log");
>
> This, however, seems to be wrong.
>
> The logfile name does not belong in the extension, it belongs in the
> configuration file. I think the extension should set it's "stream id" or
> whatever you want to call it, and then it should be possible to control in
> postgresql.conf where that log is sent.

Doesn't the last paragraph of

https://www.postgresql.org/message-id/11412.1503912190%40localhost

address your concerns?

> Also, what if this extension is loaded on demand in a session and not via
> shared_preload_libraries? It looks like the syslogger only gets the list of
> configured streams when it starts?

Yes, the syslogger gets the list of streams only when it starts, so the
extension that wants to use this feature needs to provide the file information
via shared_preload_libraries. I consider it sufficient because various
existing logging-related GUCs also can't be changed on-the-fly.

> In short, I think the solution should be more generic, and not "just for extensions".

o.k. Any idea about dividing the streams into categories? Should they for
example correspond somehow to categories of GUC variables?

> I completely missed this thread when I did my quick-wip at
> https://www.postgresql.org/message-id/flat/CABUevExztL0GORyWM9S4tR_Ft3FmJbRaxQdxj+BQZjpvmRurdw(at)mail(dot)gmail(dot)com#CABUevExztL0GORyWM9S4tR_Ft3FmJbRaxQdxj+BQZjpvmRurdw@mail.gmail.com
> -- some of the changes made were close enough that I got the two confused :)
> Based on the feedback of that one, have you done any performance checks?

I don't expect mere routing of messages into multiple files to bring any
overhead. I'll run some tests, just out of curiosity.

--
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at