Re: Configuration of statistical views

Tom Lane wrote:
> Jan Wieck <JanWieck@yahoo.com> writes:
> >> backend start/stop events probably need to be reported whenever the
> >> postmaster variable is set, even if all the USERSET variables are off.
>
> >     I  don't consider backend start/stop messages to be critical,
> >     although we get  some  complaints  already  about  connection
> >     slowness  -  well, this is somewhere in the microseconds. And
> >     it'd be a little messy because the start message is  sent  by
> >     the backend while the stop message is sent by the postmaster.
> >     So where exactly to put it?
>
> This is exactly why I think they should be sent unconditionally.
> It doesn't matter if a particular backend turns its reporting on and
> off while it runs (I hope), but I'd think the stats collector would
> get confused if it saw, say, a start and no stop message for a
> particular backend.
>
> OTOH, given that we need to treat the transmission channel as
> unreliable, it would be a bad idea anyway if the stats collector got
> seriously confused by not seeing the start or the stop message.
   Hmmm  -  that's  a  good  point.  Right now, the collector is   totally lax on  all  of  that.  Missing  start
packet -  no   problem, we create the backend slot on the fly. Missing stats   packet - well, the counters aren't 100%
correct, so  be  it.   But  OTOH  it  causes  him  to  remember the dead backend for   postmaster lifetime in case of a
missingstop.  Except a  PID   wraparound   causes   a   fix   someday.    Maybe  it  should   periodically (every 10
minutesor even longer) check  with  a   zero-kill  if  all  the  backends  it  knows about are really   alive.
 


Jan

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