question about group_vars

I've been busy and out of the loop, looking through the documentation I see a lot of new functionalities have been added to ansible!

The one I am most exited about is the group_vars, we have already implemented something similar through a bunch of includes, but this makes it much simpler, but have questions about it. Assuming this host file:

     # host file
     [postgres_master]
     damaster

     [postgres_slave]
     daslave

     [postgres:children]
     postgres_master
     postgres_slave

Do I just create this structure:
group_vars/postgres
           /postgres_master
           /postgres_slave

Will "damaster" load variables from both group_vars/postgres and group_vars/postgres_master?

Can I add the .yml or .yaml extension to the group_vars files, or do they need to be extension-less (some editor only do syntax highlighting when the right extension is there)?

Thanks.

Hi Yves,