Re: How should pg_standby get over the gap of timeline?

On Sat, Nov 22, 2008 at 6:28 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> My worry is that there has not been an exhaustive analysis. "Almost
> correct" and "probably correct" is not the same thing as "correct". We
> need to look through all of the changes that occur at the end of
> recovery to be certain we can do this. Luckily normal data blocks don't
> know anything about such state changes, so that is a good start. We must
> look at

It's reasonable worry. Thanks a lot, Simon. I will examine it next time
(probably 8.5).

And, I'd like to clear up which recovery method is safe now. Althogh
I think as follows, is it right?

Safe (proved to be safe):
- PITR with a base backup.
That is, we don't always need a fresh backup when setting up, and
can make the standby catch up by using an old or fresh backup.
If we can use an old backup, I think it might be worth changing
pg_standby to get over the gap of timeline. What is your opinion?

- PITR with a database cluster including a recovery restart point.
That is, we can make the standby catch up without a base backup
after it fails.

Not safe (further examination is needed):
- PITR with a database cluster not including a recovery restart point.
That is, we cannot make the standby (old primary) catch up without
a base backup.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center