RE: [postgres_fdw] add local pid to fallback_application_name

Dear Tom,

Thank you for replying!

> I don't think this is a great idea as-is. People who need to do this
> sort of thing will all have their own ideas of what they need to track
> --- most obviously, it might be appropriate to include the originating
> server's name, else you don't know what machine the PID is for.

I thought this is not big problem because hostname (or IP address) can be
added to log_line_prefix. I added only local-pid because this is the only thing
that cannot be set in the parameter.

> So I think most people with this sort of requirement will be overriding
> the default application name anyway, so we might as well keep the
> default behavior simple.

Yeah, this patch assumed that application_name will be not overridden.
There is an another approach that PID adds to application_name, but it might be stupid.

> What would be better to think about is how to let users specify this
> kind of behavior for themselves. I think it's possible to set
> application_name as part of a foreign server's connection options,
> but at present the result would only be a constant string. Somebody
> who wished the PID to be in there would like to have some sort of
> formatting escape, say "%p" for PID. Extrapolating wildly, maybe we
> could make all the %-codes known to log_line_prefix available here.

I think your argument is better than mine. I will try to implement this approach.
If anyone has another argument please tell me.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED