quoted_columns_for_index

# File activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb, line 975
        def quoted_columns_for_index(column_names, options = {})
          option_strings = Hash[column_names.map {|name| [name, '']}]

          # add index sort order if supported
          if supports_index_sort_order?
            option_strings = add_index_sort_order(option_strings, column_names, options)
          end

          column_names.map {|name| quote_column_name(name) + option_strings[name]}
        end