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

[Tatsuo Ishii]

> 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? 

You can issue "smart shutdown" command to pgpool. pgpool will wait
until all clients exit (that means there's no live backend any more)
then exits itself. Then you shutdown the secondary PostgreSQL and
retsrat pgpool.

What do you think?
--
Tatsuo Ishii

> > -----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
> > 
>