On Fri, 2010-10-15 at 21:41 +0900, Fujii Masao wrote: > As the result of the discussion, I think that we need the following two > parameters for the case where the standby goes down.
> * replication_timeout > This is the maximum time to wait for the ACK from the standby. If this > timeout expires, the master closes the replication connection and > disconnects the standby. This parameter is just used for the master > to detect the standby crash or the network outage. > > We already have keepalive parameters for that purpose. Yes, I had thought we would just use the keepalives... > But they cannot > detect the disconnection in some cases. So replication_timeout needs > to be introduced for sync rep. When exactly don't the keepalives work? > * allow_standalone_master > This specifies whether we allow the master to process transactions > alone when there is no connected and sync'd standby. > > If this is false, all the transactions on the master are blocked until > sync'd standby has appeared. Of course, this happen not only when > replication_timeout expires but also when we start the master alone > at the initial setup, when the master detects the disconnection by > using keepalive parameters, and when the standby is shut down normally. > People who want 'wait-forever' will disable this parameter to reduce > the risk of data loss. > > OTOH, if this is true, the absence of sync'd standby doesn't prevent > the master from processing transactions alone. People who want high > availability even though the risk of data loss increases will enable > this parameter. OK -- Simon Riggs www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
