[Pgpool-general] Pgpool-II and Slony-I

[Tatsuo Ishii]

> > Sorry for the poor documentations. Actually the settings
> > for using
> > master/slave mode is surprisingly simple. If you are
> > running Slony
> > master on host foo port 5432 and a slave on host bar port
> > 5433, the
> > settings for pgpool.conf would look something like:
> > 
> > backend_hostname0 = 'foo'
> > backend_port0 = 5432
> > backend_weight0 = 1
> > backend_data_directory0 = '/usr/local/pgsql/data'
> > backend_hostname1 = 'bar'
> > backend_port1 = 5433
> > backend_weight1 = 1
> > backend_data_directory1 = '/usr/local/pgsql/data'
> > 
> > replication_mode = false
> > master_slave_mode = true
> > load_balance_mode = true
> > 
> > In the master/slave mode, pgpool will throw all DMLs to
> > master
> > only. SELECTs will be thrown to master and slave.
> > 
> 
> Thanks Tatsuo, that helps but I'm full of questions...
> 
> Does it support a 3rd slave?  

Of course.

> I presume it works when the machines are on different hosts and the
> same port? 

You can use any combination of hosts and ports. For example, if you
only have a machine, you could:

backend_hostname0 = 'foo'
backend_port0 = 5432
backend_weight0 = 1
backend_data_directory0 = '/usr/local/pgsql/data'
backend_hostname1 = 'foo'
backend_port1 = 5433
backend_weight1 = 1
backend_data_directory1 = '/usr/local/pgsql/data'

> How is the backend_data_directory used?

If my memory is correct, it does nothing with master/slave mode. It
only is related to replication mode + on line recovery.

> My install references master_backend_hostname etc instead of backend_hostname0 etc, should I change these or will it support tertiary_backend_hostname etc?

master_backend_hostname is a directive name for pgpool(I). I strongly
recommend to use pgpool-II.
--
Tatsuo Ishii
SRA OSS, Inc. Japan