[Pgpool-general] continue functioning on backend mismatch

[Jaume Sabater]

On Wed, Nov 11, 2009 at 7:25 AM, Asaf Ohaion <asaf at lingnu.com> wrote:

> I'm testing the replication function for some time now, trying
> to move to production, one of the biggest things preventing me
> from doing so :
>
> when theres a mismatch between the two backends, my client is
> stuck with it until I fix it, I would like, in such case,
> to continue working only with the primary backend,
> letting me fix the problem later on.
> is this possible ?

I believe that your client should be aware of the returned error (say
capture the exception) and retry the job. When retrying, the queries
would be sent to the master node only and would work fine (slave node
would now be degenerated).

But I also recall work being done in the last 3 or 4 minor versions of
pgpool-II regarding this sort of issues, although it was not covering
all cases. Perhaps Tatsuo can provide more detailed information (I
recall there was a reason why you don't want some queries to "just be
passed to the other node and continue", but I have fishy memory).

-- 
Jaume Sabater
http://linuxsilo.net/

"Ubi sapientas ibi libertas"