controller.rb

Data.with_schema('schema_name').all

model.rb

def self.with_schema(schema_name)
    class_name = self.name + schema_name.camelize
    table_name = self.table_name
    if !Object.const_defined?(class_name)
      Object.const_set(
        class_name, Class.new(self) do
          self.table_name = "#{schema_name}.#{table_name}"
        end
      )
    end
    class_name.constantize
  end