Re: [BUG] Checkpointer on hot standby runs without looking checkpoint_segments

Thank you for sugestion.

> This still makes catching up in standby mode slower, as you get
> many more restartpoints. The reason for ignoring
> checkpoint_segments during recovery was to avoid that.

I may have a misunderstanding around there, or your intention.

I understand that standby creates no WAL archive, and can not
recover from WAL archive, and both master and standby keeps WAL
segment no longer than about them for about 2 * 1h, spans two
maximum checkpoint_timeout intervals and some more.

Could you please tell me whether the above is correct?

If you meant crash recovery with the word 'recovery', there's
WALs no more than for 2+ hours, far less than days, or weeks
long.

Otherwise, if you meant archive recovery, this patch does not
change the behavior of archive recovery as far as I
intended. This patch intended to change the behavior of standby
under WAL shipping.

If it is correct and the patch works correctly, your anxiety
below should disappear, I hope. And if not correct, I *MUST*
avoid such negative impacts on the functions out of the target -
governing checkpoint progress on standby server shipping WALs
from its master.

> Maybe it's still better than what we have currently, I'm not
> sure, but at least it needs to be discussed. Would be good to
> do some performance testing of recovery with various
> checkpoint_segments and _timeout settings, with and without
> this patch.

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center

== My e-mail address has been changed since Apr. 1, 2012.