    # File lib/memcache/migration.rb, line 7
        def self.up
          create_table table, :id => false do |t|
            t.string    :prefix, :null => false
            t.string    :key,    :null => false
            t.text      :value,  :null => false
            t.timestamp :expires_at
            t.timestamp :updated_at
          end

          add_index table, [:prefix, :key], :unique => true
          add_index table, [:expires_at]
        end