On Thu, Nov 15, 2012 at 12:55 AM, Amit Kapila <amit.kap...@huawei.com> wrote: > Now user can use this utility to decide if new-standby has max LSN greater > than max LSN of new-master he needs to use fullback-up on new-standby. Is my > understanding right?
No. The maximum LSN of data pages in new-standby should be compared with the last replayed LSN (IOW, the last valid LSN of previous timeline) of new-master. >>OTOH, there can be the case >> where new master has already been ahead of the startpoint. > > > But in this case, there is no need for this utility. Right? No. The above comparison is required in this case. > >> > So now user may not be able to decide whether he needs to do >> incremental or >> > full backup from new master, >> > is this the case you are trying to point? >> >> Sorry, I could not parse this comment. Could you elaborate your concern >> again? > > I wanted to understand the usecase mentioned by you for this utility. > As far as I can understand is that it will be used to decide that on > new-standby (old-master) whether a full backup is needed from > New-master(old-standby). Yes. > And that situation can occur when new-standby has startpoint LSN greater > than new-master? Whether the backup is required has nothing to do with the startpoint. The backup is required when the data page in old-master precedes the last applied LSN in old-standby (i.e., new-master) at the moment of the failover. Without the backup, there is no way to revert the data which is ahead of new-master. Regards, -- Fujii Masao -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
