On Thursday, September 27, 2012 6:30 AM Josh Berkus wrote: > > Yes that is correct. I thought timeline change happens only when > somebody > > does PITR. > > Can you please tell me why we change timeline after promotion, > because the > > original > > Timeline concept was for PITR and I am not able to trace from code > the > > reason > > why on promotion it is required? > > The idea behind the timeline switch is to prevent a server from > subscribing to a master which is actually behind it. For example, > consider this sequence: > > 1. M1->async->S1 > 2. M1 is at xid 2001 and fails. > 3. S1 did not receive transaction 2001 and is at xid 2000 > 4. S1 is promoted. > 5. S1 processed an new, different transaction 2001 > 6. M1 is repaired and brought back up > 7. M1 is subscribed to S1 > 8. M1 is now corrupt. > > That's why we need the timeline switch.
Thanks. I understood this point, but currently in documentation of Timelines, this usecase is not documented (Section 24.3.5). 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
