Two important characteristics of files are Data Organization and Method of Access . Data organization , refers to the way the records of the file are organized on the backing storage device. Relative - Relative record number based organization. Indexed - Index based organization. Method of access , refers to the way in which records are accessed.
Some organizations are more versatile than others.
In a Sequential file the records are arranged serially, one after another, like cards in a dealing shoe. The only way to access records in a Sequential file, is serially. A program must start at the first record and read all the succeeding records until the required record is found or until the end of the file is reached. The ordering of the records in a file has a significant impact on the way in which it is processed and the processing that can be done on it. In an unordered file, the records are not in any particular order.