On Tue, 4 Oct 2005, Simon Riggs wrote:
What would constitute an intermediate rebuild? Of course the system is up and
live and having data added to it. How would one restore from multiple
timelines?
This is only if you are back up and working on the went-down box:
intermediate rebuild: I mean that you will have to restore the data from
the period of switchover, manually extract the relevant data with SQL
and then re-insert those changes yourself and resolve conflicts.
I think we're likely out of luck here, but let me provide a few more details
so you might give me a better idea.
We are up on the went-down box with a pg_dump restore from the 3:30a.m. of the
previous day. We have WAL files available from the box that was up during the
failure of the primary. What I do not have is a base backup of the box which
was up for part of the day while we brought up the went-down box. So, unless
there is some method of replaying WAL files by hand one at a time, I think we
are out of luck, no?
There isn't a process to merge the two log streams. The same txnid will
have been used on both servers to refer to separate transactions, so
there can be no automated way of resolving the data. It has to be done
using business domain knowledge rather than log data.
All of that's no different from any other RDBMS, as I'm sure you know.
I do know, and in fact, I think PITR is great, I just wish we had thought
about the corner case of the servers switching roles between the biweekly base
backups.
--
Jeff Frost, Owner <jeff@xxxxxxxxxxxxxxxxxxxxxx>
Frost Consulting, LLC http://www.frostconsultingllc.com/
Phone: 650-780-7908 FAX: 650-649-1954
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