On Tuesday, June 18, 2013 12:18 AM Sawada Masahiko wrote: > On Sun, Jun 16, 2013 at 2:00 PM, Amit kapila <amit.kap...@huawei.com> > wrote: > > On Saturday, June 15, 2013 8:29 PM Sawada Masahiko wrote: > > On Sat, Jun 15, 2013 at 10:34 PM, Amit kapila > <amit.kap...@huawei.com> wrote: > >> > >> On Saturday, June 15, 2013 1:19 PM Sawada Masahiko wrote: > >> On Fri, Jun 14, 2013 at 10:15 PM, Amit Kapila > <amit.kap...@huawei.com> wrote: > >>> On Friday, June 14, 2013 2:42 PM Samrat Revagade wrote: > >>>> Hello, > >>> > >>>>>> We have already started a discussion on pgsql-hackers for the > problem of > >>>>>> taking fresh backup during the failback operation here is the > link for that: > >>>>>> > >>>>>> > >>>>>> http://www.postgresql.org/message-id/CAF8Q-Gxg3PQTf71NVECe- > 6OzRaew5pWhk7yQtb > >>>>>> jgwrfu513...@mail.gmail.com > >>>>>> > >>>>>> Let me again summarize the problem we are trying to address. > >>>>>> > >>>>>> > >>>>> How will you take care of extra WAL on old master during > recovery. If it > >>>>> plays the WAL which has not reached new-master, it can be a > problem. > >> > >>>> you means that there is possible that old master's data ahead of > new > >>>> master's data. > >> > >>> I mean to say is that WAL of old master can be ahead of new > master. I understood that > >>> data files of old master can't be ahead, but I think WAL can be > ahead. > >> > >>>> so there is inconsistent data between those server when fail back. > right? > >>>> if so , there is not possible inconsistent. because if you use GUC > option > >>>> as his propose (i.g., failback_safe_standby_mode = remote_flush), > >>>> when old master is working fine, all file system level changes > aren't > >>>> done before WAL replicated. > >> > >>> Would the propose patch will take care that old master's WAL is > also not ahead in some way? > >>> If yes, I think i am missing some point. > > > >> yes it will happen that old master's WAL ahead of new master's WAL > as you said. > >> but I think that we can solve them by delete all WAL file when old > >> master starts as new standby. > > > > I think ideally, it should reset WAL location at the point where new > master has forrked off. > > In such a scenario it would be difficult for user who wants to get a > dump of some data in > > old master which hasn't gone to new master. I am not sure if such a > need is there for real users, but if it > > is there, then providing this solution will have some drawbacks.
> I think that we can dumping data before all WAL files deleting. All > WAL files deleting is done when old master starts as new standby. Can we dump data without starting server? With Regards, Amit Kapila. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
