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Re: pitr replica dies on startup

From: Jeff Frost <jeff(at)frostconsultingllc(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: pitr replica dies on startup
Date: 2007-09-01 02:09:02
Message-ID: Pine.LNX.4.64.0708311908090.11463@discord.home.frostconsultingllc.com (view raw or flat)
Thread:
Lists: pgsql-admin
On Fri, 31 Aug 2007, Jeff Frost wrote:

> On Fri, 31 Aug 2007, Tom Lane wrote:
>
>> Jeff Frost <jeff(at)frostconsultingllc(dot)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.

Sure enough, commenting out the mv fixes the problem.  Now everything starts 
up just fine.  So, I'll have to re-engineer the script not to do that.

Thanks again Tom!

-- 
Jeff Frost, Owner 	<jeff(at)frostconsultingllc(dot)com>
Frost Consulting, LLC 	http://www.frostconsultingllc.com/
Phone: 650-780-7908	FAX: 650-649-1954

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