Le 28/01/2011 08:31, Tatsuo Ishii a écrit : >> Le 28/01/2011 01:16, Tatsuo Ishii a écrit : >>>> One of my customers asks me today why pgpool doesn't check, from time to >>>> time, that the backend is now available in connection pool mode. >>>> >>>> Here is what we did with a pgpool 3.0.1, configured only for connection >>>> pooling and health checking: >>>> >>>> * start postgresql (pg_ctl start) >>>> * start pgpool (pgpool -f etc/pgpool.conf start) >>>> * every connection works fine >>>> * stop postgresql (pg_ctl start) >>>> * health check detects the unavailability of the backend >>>> and changes status of node 0 to 3 >>>> * no connection, which is good because backend is unavailable >>>> * start postgresql (pg_ctl start) >>>> * and the node still remains in status 3. >>>> >>>> What I would like to have is a way to check if the backend is now >>>> available. And reattach it if it is. All intern to pgpool. Any reason >>>> why not to do so? >>>> >>>> I can have misread the documentation, and I understand why this cannot >>>> happen in replication mode or master/slave mode. But in connection >>>> pooling only mode, I don't get it. >>>> >>>> If it seems to be a nice feature to have, I'm interested in working on >>>> this. >>> >>> I'm not sure if it's good feature. Say you have 2 DB servers and one >>> of their network connections goes shakey. It continues to up and down >>> every 10 seconds. If pgpool has such a feature, pgpool repeatedly does >>> failover every 10 seconds, which will break existing client connection >>> every 10 seconds. I'm sure the user is not happy with this situation. >> >> You can use two PostgreSQL servers in pooling mode? how does that work? > > You can use the second server as the backup server. If the master > server godes down, degenration happens and pgpool starts to use the > second server. >
Oh OK. Interesting, I didn't know that. That explains why it degenerates and checks for another backend. I still see an interest to have this when a user has only one backend and is only in pooling mode. >> I'm speaking only of the pooling mode, without replication and load >> balancing. In this case, if the network goes up and down continuously, >> you continuously loose the connection and have to reattach node 0. > -- Guillaume http://www.postgresql.fr http://dalibo.com _______________________________________________ Pgpool-hackers mailing list [email protected] http://pgfoundry.org/mailman/listinfo/pgpool-hackers
