Hi, I want to be able to have a primary/standby PostgreSQL setup with streaming replication and using pgPool to deal with the load balancing and auto failover. One question I have is can I have 2 instances of pgPool pointing to the same database servers? In addition to this, what if pgPool1 and the primary were in one data centre, pgPool2 and the standby were in another data centre, then connectivity went down between the data centres. On top of this would be a connection load balancer to map incoming connections to one of the pgPool instances (in case one of the pgPool instances dies). It looks like pgPool2 would promote the standby to a primary, then when connectivity was restored, there'd be a split brain issue where write queries would randomly hit one of the servers, making them instantly out of sync. This seems like it should be a very common setup, so does pgPool have provisioning for this, like having a 3rd pgPool to manage them somehow?
Also, if there was a primary and 2 standbys, and the primary goes down, which promotes standby1, how does standby2 then subscribe to standby1 automatically? And how does pgPool then know how to trigger failover on the next standby if the new primary fails? And when I set up pgPool today with a primary and standby using streaming replication, queries only seemed to hit the primary. Any idea what I could have missed? Aren't SELECT queries supposed to be randomly sent to one of the servers? I ran queries several times and never did any hit the standby. Just to note, the config changes were something like this: failover_command = '<command to put trigger file on 1st standby' backend_* = <these ones are all commented out as I'm only using pgPool for load balancing> replication_mode = false load_balance_mode = true replicate_select = false backend_hostname0/port0... = <this was set to the primary> backend_hostname1/port1... = <this was set to the first standby> Thanks Thom _______________________________________________ Pgpool-general mailing list [email protected] http://pgfoundry.org/mailman/listinfo/pgpool-general
