[Pgpool-general] RE: Bad degeneration when shutting down secondary backend

[Pablo Milano]

I was thinking in a workaround.
If I can detect that pgpool does not have any live backend, I can restart
the daemon, so it will re-detect the really alive backend and will perform
the correct degeneration. This can be done externally by a shell script.
Maybe, pgpool can restart himself when both backends are shut down. ¿What do
you think about this? ¿May it solve the problem? 

> -----Original Message-----
> From: Tatsuo Ishii [mailto:t-ishii at sra.co.jp] 
> Sent: Jueves, 18 de Agosto de 2005 07:27 p.m.
> To: Pablo G. Milano
> Cc: pgpool-general at pgfoundry.org
> Subject: Re: Bad degeneration when shutting down secondary backend
> 
> > > Unfortunately pgpool's data difference detection is not 
> perfect, and
> > > sometimes it raise false alarm. That's why I recommend setting
> > > replication_stop_on_mismatch to false.
> > 
> > The point here is that, if I shut down the secondary 
> backend in a working
> > production environment, degeneration mode performs in the wrong way
> > (shutting down the master backend instead of the 
> secondary). As a result,
> > the entire environment would be down (secondary is down and 
> master is shut
> > down by pgpool).
> > This behaviour may be avoided by setting 
> "replication_stop_on_mismatch" to
> > false, but on the other hand, if a real data mismatch 
> exist, it won't be
> > detected.
> > Is there any other way to avoid pgpool detection of a data 
> mismatch when one
> > backend is being shut down?
> 
> If it's a schedule down time, you could use "switch" to tell pgpool
> explicitly the secondary server is going down.
> 
> $ pgpool -s secondary switch
> 
> Does this help?
> --
> Tatsuo Ishii
>