On Sun, Aug 7, 2016 at 9:29 PM, Colin Morelli <colin.more...@gmail.com> wrote:
> Venkata, > > Thanks for the reply. Unfortunately something like PgPool still won't > create the replication slots on all hosts, and record the LSN in a way that > is reusable on the secondary. > Yes, thats correct, pgPool does not have anything to do with replication slots. That is something which you need to manually configure. > This sort of puts logical decoding at odds with HA, correct? In the case > of master failover, there's no way to: a) know where in the stream you read > to, or b) convert that to something that can be understood by a replica > that's about to be promoted. > Can you please clarify, what did you exactly mean here ? are you referring to cascading standbys or something ? Failover is something which application has to do, to reconnect to the promoted standby. As far as logical decoding is concerned, you need to have a replication slot configured for the new master to ensure all the WALs which are not replicated to standby are retained. After promotion, the standby database becomes a standalone instance and the replication must be re-enabled. You can automate the standby promotion using tools like pgpool-II or pacemaker. I am trying to differentiate standby-promotion and failover mechanism here. Are there any scheduled improvements here either for 9.6 or 9.7? > I am not 100% sure, if there is anything developed from an failover mechanism perspective. Regards, Venkata B N Fujitsu Australia
