Re: data loss with pg_standby when doing a controlled failover

On Mon, Apr 6, 2009 at 7:37 AM, Andreas Pflug <pgadmin(at)pse-consulting(dot)de>wrote:

> Running 8.3.7, I have a warm standby configuration with a
> archive_timeout of 10min.
>
> It's obvious that there's a 10min period where data could be lost if the
> master fails and the warm standby server has to take over. What's not
> obvious is that this is true even if the master server is shut down
> regularly, because it will not write out a last log segment to the
> archive. As a consequence, when doing a controlled failover (for
> maintenance purposes or so) all data changed after the last archive copy
> will be lost.
> IMHO this should be mentioned in the docs explicitly (I find it quite
> surprising that data can be lost even if the system is shutdown
> correctly), or better when shutting down the postmaster should spit all
> log segments containing all changes when archiving is on so the warm
> standby server can catch up.

You make an excellent point. If you're looking for a way to mitigate this
risk, run:

select pg_switch_xlog() ;

Before shutting down.

--Scott

>
>
> Regards.
> Andreas
>
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