File Organizations

System designers choose to organize, access, and process records and files in different ways depending on the type of application and the needs of users. The three commonly used file organizations used in business data processing applications are - sequential, direct and indexed sequential organizations. The selection of a particular file organization depends upon the type of application. The best organization to use in a given application is the one that happens to meet the user's needs in the most effective and economical manner. In making the choice for an application, designers must evaluate the distinct strengths and weaknesses of each file organization. File organization requires the use of some key field or unique identifying value that is found in every record in the file. The key value must be unique for each record of the file because duplications would cause serious problems. In the payroll example, the employee code field may be used as the key field.