# File lib/migration.rb, line 103
    def create_index(table_name, *columns_and_options)
      if columns_and_options.last.is_a?(Hash)
        opts = columns_and_options.pop
      else
        opts = {}
      end
      columns = columns_and_options.flatten

      opts[:name] ||= "#{opts[:unique] ? 'unique_' : ''}index_#{table_name}_#{columns.join('_')}"

      execute "CREATE \#{opts[:unique] ? 'UNIQUE ' : '' }INDEX \#{quote_column_name(opts[:name])} ON\n\#{quote_table_name(table_name)} (\#{columns.map { |c| quote_column_name(c) }.join(', ') })\n".compress_lines
    end