Re: [pcp] logger PMDA review

[Ken McDonell <kenj at internode dot on dot net>]

On Mon, 2011-04-18 at 13:24 -0500, David Smith wrote:
> ...
> 
> > - might want to revisit using dynamic metric names versus metric
> >   instances, dynamic names generally a bit more complicated to code.
> >   (removes need to restrict/check names in Install too, although they
> >   do need to be unique)
> 
> On the dynamic metric name issue versus metric instances issue, I looked
> into that a bit.  I was considering making each logfile a separate
> instance.  However, I couldn't figure out from the client point of view
> how to "subscribe" to only one instance of a particular metric.  It
> seemed wrong to make the client consume data for multiple files when it
> was only interested in one file's data.
> 
> If I'm wrong here, I'll be happy to rethink.
> 

Clients use pmAddProfile and pmDelProfile to allow selection of one,
some or all of the instances for each instance domain ... once made, the
profile remains "sticky" for each subsequent pmFetch ... the default is
for pmFetch to return all instances for all instance domains.  This is
how pmval -i instance or pmevent metric[instance] works.

I suspect an instance domain is going to be a cleaner long-term solution
than dynamic metrics in the PMNS for your case of multiple log files
being processed.