multiple database connections

For multiple database connections, is it better to have a mixin included into the model that does a establish connection on included event or is it better to have an abstract class that establishes the connnection and inherit from the abstract class? In particular, how do Rails handle database connections? It is supposed to use a connection pool, does the pooling break if you use a mixin?

Mixin:

module CustomConnect

  def self.included(base)     config = ActiveRecord::Base.configurations["custom_"+RAILS_ENV]     base.establish_connection(config)   end

end

and then you do a

class abc < ActiveRecord::Base

include CustomConnect

end

Inheritance:

class CustomConnect < ActiveRecord::Base

  self.abstract_class = true   config = ActiveRecord::Base.configurations["custom_"+RAILS_ENV]   establish_connection(config)

end

class abc < CustomConnect

end

When you have a significant number of models, how are database connections handled and which approach is better?

Does anyone have an input on connection pooling and which approach is better?