Re: BUG #8686: Standby could not restart.

Hi Heikki,
Thanks for your confirmation and comments.

>
>
> /*
>> * Initialize shared replayEndRecPtr,
>> lastReplayedEndRecPtr, and
>> * recoveryLastXTime.
>> *
>> * This is slightly confusing if we're starting from an
>> online
>> * checkpoint; we've just read and replayed the
>> checkpoint record, but
>> * we're going to start replay from its redo pointer,
>> which precedes
>> * the location of the checkpoint record itself. So even
>> though the
>> * last record we've replayed is indeed ReadRecPtr, we
>> haven't
>> * replayed all the preceding records yet. That's OK for
>> the current
>> * use of these variables.
>> */
>> SpinLockAcquire(&xlogctl->info_lck);
>> xlogctl->replayEndRecPtr = ReadRecPtr;
>> xlogctl->lastReplayedEndRecPtr = EndRecPtr;
>> xlogctl->recoveryLastXTime = 0;
>> xlogctl->currentChunkStartTime = 0;
>> xlogctl->recoveryPause = false;
>> SpinLockRelease(&xlogctl->info_lck);
>>
>
> I think we need to fix that confusion. Your patch will do it by not
> setting EndRecPtr yet; that fixes the bug, but leaves those variables in a
> slightly strange state; I'm not sure what EndRecPtr points to in that case
> (0 ?), but ReadRecPtr would be set I guess.
>
Yes, the values were set like below.
ReadRecPtr:1/8E7F0B0
EndRecPtr:0/0

>
> Perhaps we should reset replayEndRecPtr and lastReplayedEndRecPtr to the
> REDO point here, instead of ReadRecPtr/EndRecPtr.
>

I made another patch.
I added a ReadRecord to make sure the REDO location is present or not.
The similar process are done when we use backup_label.

Because the ReadRecord returns a record already read,
I set ReadRecPtr of the record to EndRecPtr.
And also I set record->xl_prev to ReadRecPtr.
As you said, it also worked fine.

I'm not sure we should do same thing when crash recovery occurs, but now I
added the process when archive recovery is needed.

Please see attached patch.

regards,
---------------------
Tomonari Katsumata