create_index (DataMapper::Migration)

    # File lib/dm-migrations/migration.rb, line 101
        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