On Fri, 31 Aug 2007, Tom Lane wrote:
> Jeff Frost <jeff@frostconsultingllc.com> writes:
>> Why does it request it twice?
>
> I think the reason is that the rollforward cycle is
>
> fetch next segment into RECOVERYXLOG
> process segment
> unlink RECOVERYXLOG
>
> and only when the "fetch" step fails does it realize it's done. So then
> it has to figure out which segment it wants to start extending and fetch
> that into the real name of the segment.
>
> We could probably rejigger this to avoid a duplicate fetch in common
> cases, but I'm worried that we couldn't guarantee it in every case ---
> edge cases like the last valid xlog record ending right at a segment
> boundary might be trouble. If the recovery script has to handle the
> situation sometimes, it's probably best to make it do so on a regular
> basis ---
That all seems reasonable enough. Is it in the docs somewhere? I didn't find
anything like this mentioned. If not, could we get it added as a note?
> would you like to have only found out about this when you were
> trying to revive your database at 4AM?
Oh, definitely not! But then again, that's why I was testing it. :-) I just
wish the guy who came before me and wrote the script had tested it. But, no
big deal, I'll just update the script to deal with it.
As always, thanks Tom! I'll report back if that's the fix.
--
Jeff Frost, Owner <jeff@frostconsultingllc.com>
Frost Consulting, LLC http://www.frostconsultingllc.com/
Phone: 650-780-7908 FAX: 650-649-1954
