On Tue, Oct 12, 2010 at 11:50 PM, Robert Haas <robertmh...@gmail.com> wrote: > There's another problem here we should think about, too. Suppose you > have a master and two standbys. The master dies. You promote one of > the standbys, which turns out to be behind the other. You then > repoint the other standby at the one you promoted. Congratulations, > your database is now very possible corrupt, and you may very well get > no warning of that fact. It seems to me that we would be well-advised > to install some kind of bullet-proof safeguard against this kind of > problem, so that you will KNOW that the standby needs to be re-synced. > I mention this because I have a vague feeling that timelines are > supposed to prevent you from getting different WAL histories confused > with each other, but they don't actually cover all the cases that can > happen. >
Why don't the usual protections kick in here? The new record read from the location the xlog reader is expecting to find it has to have a valid CRC and a correct back pointer to the previous record. If the new wal sender is behind the old one then the new record it's sent won't match up at all. -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
