Re: [HACKERS] For review: Server instrumentation patch

Andreas Pflug wrote:
> Bruce Momjian wrote:
> 
> >> BTW, it surprised me that one of the functions (don't remember 
> >> which one) expected the log files to be named in a very specific 
> >> fashion.  So there's no flexibility for changing the log_prefix. 
> >> Probably it's not so bad, but strange anyway.  Is this for 
> >> "security" reasons?
> 
> The logger subprocess patch originally didn't allow changing the the 
> logfile name pattern, to make sure it can be interpreted safely at a 
> later time. There's simply no way to mark the file with a timestamp 
> without the risk of it being arbitrarily modified by file commands, thus 
> screwing up the order of logfiles. Later, there was the request to 
> alternatively append a timestamp instead of a date pattern, to use 
> apache logging tools that will probably access the logfiles directly 
> anyway. This ended up in the log_filename GUC variable.
> 
> > 
> > Righ, pg_logdir_ls() was the function.  My feeling is that the 
> > application has access to the log_directory and log_filename values 
> > and can better and move flexibly filter pg_ls_dir() on the client end
> >  than we can do on the server. It just seemed like something that we 
> > better done outside the server.
> 
> Outside the server means pure SQL, if you don't want to drop psql as
> client. So how would your query to display all all available _logfiles_
> look like? You'd need to check for a valid date, besides interpreting 
> pg_strfime's patterns. Doesn't sound exactly like fun, but I'm keen to 
> see how your equivalent to

I don't assume people using psql will care about the current log files ---
it would be something done in C or another application language.  Aren't
the file names already ordered based on their file names, given the
default pattern, postgresql-%Y-%m-%d_%H%M%S.log?

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