create_indexes.rb

  namespace :db do
    task :create_indexes => :environment do
    #
      begin
        Rails.application.eager_load!
      rescue Object => e
      end

    #
      begin
        Bundler.require(:default, :assets, 'production')
      rescue Object => e
      end

    #
      to_index_models = [] 

      ObjectSpace.each_object(Module) do |object|
        begin
          to_index_models.push(object) if object.respond_to?(:create_indexes)
        rescue Object => e
          warn "failed on: #{ object }.respond_to?(:create_indexes)"
        end
      end

    #
      to_index_models.sort! do |a, b|
        begin
          a.name <=> b.name
        rescue Object
          0
        end
      end

    #
      begin
        to_index_models.uniq!
      rescue Object
      end

    #
      to_index_models.each do |model|
        begin
          model.create_indexes
          puts "indexed: #{ model }"
        rescue Object => e
          warn "failed on: #{ model }#create_indexes"
        end
      end
    end
  end