```ruby
module ActiveAdmin
  module Inputs
    module Filters
      class SelectInput < ::Formtastic::Inputs::SelectInput
        include Base

        def input_name
          return method if seems_searchable?

          searchable_method_name + (multiple? ? '_in' : '_eq')
        end

        def searchable_method_name
          if searchable_has_many_through?
            "#{reflection.through_reflection.name}_#{reflection.foreign_key}"
          else
            name = method.to_s
            name.concat '_id' if reflection
            name
          end
        end

        # Provide the AA translation to the blank input field.
        def include_blank
          I18n.t 'active_admin.any' if super
        end

        def input_html_options_name
          "#{object_name}[#{input_name}]" # was "#{object_name}[#{association_primary_key}]"
        end

        # Would normally return true for has_many and HABTM, which would subsequently
        # cause the select field to be multi-select instead of a dropdown.
        def multiple_by_association?
          false
        end

        # Provides an efficient default lookup query if the attribute is a DB column.
        def collection
          if !options[:collection] && column
            pluck_column
          else
            super
          end
        end

        def pluck_column
          klass.reorder("#{method} asc").distinct.pluck method
        end

      end
    end
  end
end
```

Add caching of select filters' collections
user
```ruby
module ActiveAdmin
  module Inputs
    module Filters
      class SelectInput < ::Formtastic::Inputs::SelectInput
        include Base

        def input_name
          return method if seems_searchable?

          searchable_method_name + (multiple? ? '_in' : '_eq')
        end

        def searchable_method_name
          if searchable_has_many_through?
            "#{reflection.through_reflection.name}_#{reflection.foreign_key}"
          else
            name = method.to_s
            name.concat '_id' if reflection
            name
          end
        end

        # Provide the AA translation to the blank input field.
        def include_blank
          I18n.t 'active_admin.any' if super
        end

        def input_html_options_name
          "#{object_name}[#{input_name}]" # was "#{object_name}[#{association_primary_key}]"
        end

        # Would normally return true for has_many and HABTM, which would subsequently
        # cause the select field to be multi-select instead of a dropdown.
        def multiple_by_association?
          false
        end

        # Provides an efficient default lookup query if the attribute is a DB column.
        def collection
          cache_on_demand do
            if !options[:collection] && column
              pluck_column
            else
              super
            end
          end
        end

        def pluck_column
          klass.reorder("#{method} asc").distinct.pluck method
        end

        def cache_on_demand(&block)
          if options[:cache]
            cache_name = "#{klass.name}/#{method}"
            cache_name = "#{cache_name}/#{options[:cache_key].call}" if options[:cache_key]
            cache_filter(cache_name, &block)
          else
            yield
          end
        end

      end
    end
  end
end
```
assistant