Re: Broken hint bits (freeze)

On Tue, Jun 20, 2017 at 7:24 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> On Tue, Jun 20, 2017 at 7:05 PM, Sergey Burladyan <eshkinkot(at)gmail(dot)com> wrote:
>> Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> writes:
>>
>>> On Tue, Jun 20, 2017 at 3:40 PM, Sergey Burladyan <eshkinkot(at)gmail(dot)com> wrote:
>> I use pg 9.2 and "skipping restartpoint, already performed at" is from
>> src/backend/access/transam/xlog.c:8643
>> after this statement it return from CreateRestartPoint() and do not run
>> 8687 CheckPointGuts(lastCheckPoint.redo, flags);
>>
>
> You are right, so it will skip restartpoint in such a case.
>
>>> >> > Uh, as I understand it the rsync is going to copy the missing WAL file
>>> >> > from the new master to the standby, right, and I think pg_controldata
>>> >> > too, so it should be fine. Have you tested to see if it fails?
>>> >
>>> > It need old WAL files from old version for correct restore heap
>>> > files. New WAL files from new version does not have this information.
>>> >
>>>
>>> So in such a case can we run rsync once before pg_upgrade?
>>
>> I just copy last WAL from stopped old master into running old standby
>> before it shutdown and wait till it replayed. After that standby can
>> issue restartpoint at the same location as in stopped master.
>>
>
> Hmm. I think we need something that works with lesser effort because
> not all users will be as knowledgeable as you are, so if they make any
> mistakes in copying the file manually, it can lead to problems. How
> about issuing a notification (XLogArchiveNotifySeg) in shutdown
> checkpoint if archiving is enabled?
>

I have thought more about the above solution and it seems risky to
notify archiver for incomplete WAL segments (which will be possible in
this case as there is no guarantee that Checkpoint record will fill
the segment). So, it seems to me we should update the document unless
you or someone has some solution to this problem.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com