<br /><br /><div class="gmail_quote">On Thu, Nov 20, 2008 at 8:36 PM, Heikki Linnakangas <span dir="ltr"><<a
href="mailto:heikki.linnakangas@enterprisedb.com">heikki.linnakangas@enterprisedb.com</a>></span>wrote:<br
/><blockquoteclass="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex;
padding-left:1ex;"><div class="Ih2E3d"><br /></div> That seems like a dangerous assumption. What if the standby had
fallenbehind before the failover? It's not safe to failover back to the original primary in that case. We'd need some
kindof safeguards against that.<div class="Ih2E3d"><br /><br /></div></blockquote></div><br />For synchronous
replication,what if we ensure that the standby has received the WAL (atleast in its buffers) before writing it to disk
onthe primary ? If we do that, I think the old standby can never fall behind the primary and it would be easy for the
oldprimary to join back the replication without a fresh backup.<br /><br />Of course, this doesn't work for async
replication.<br/><br />Thanks,<br />Pavan<br /><br />-- <br />Pavan Deolasee<br />EnterpriseDB <a
href="http://www.enterprisedb.com">http://www.enterprisedb.com</a><br/>