Re: Recovery from multi trouble

On Thu, Dec 22, 2005 at 10:53:39AM +0000, Simon Riggs wrote:
> IMHO the problem is the deletion of the xlog file, not the error
> message.
>
> If you *did* lose an xlog file, would you not expect the system to come
> up anyway? You're saying that you'd want the system to stay down because
> of this? Would you want the system to be less available in that
> circumstance?

Well, that's what pg_resetxlog does. If you have an unclean shutdown
and you lose the xlog, you've possibly lost data. Should the postmaster
just come up and pretend nothing happened?

> I guess you want might a new postmaster option: "don't come up if you
> are damaged". Would you really use that?

Well, we have zero_damaged_pages, which is off by default.

> Overall, thank you for doing the durability testing. It is good to know
> that you're doing that and taking the time to report any issues you see.

Having a system that just blithely continues in the face of possible
data loss doesn't seem very nice either. Sure, it's nice to know about
it but is it really something we can do something about? The admin
either restores from backup or runs pg_resetxlog, accepting the fact
data will be lost. I don't think this is something postgres should be
doing on its own.

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.