CONCEPT OF COMPUTER FILES 2 - TYPES OF FILES ORGANIZATION

CONCEPT OF COMPUTER FILES 2 

FILE ORGANIZTION: MEANING AND TYPES OF FILES ORGANIZATION -SERIAL -SEQUENTIAL - INDEXED AND RANDOM

MEANING OF FILE ORGANIZATION

The term "file organization" refers to how data are stored in a file and, consequently, the method by which it can be accessed.

Types of File Organization

There are mainly four types of file organization:
1. Serial file organization
2. Sequential file organization
3. Index file organization
4. Random file organization

1. Serial file organization
Serial file is one in which the records have been stored in the order in which they have arisen. Serial files are stored in chronological order, that is, as each record is received it is stored in the next available storage position. In general, it is only used on a serial medium such as magnetic tape.

2. Sequential file organization
Sequential files are files whose records are sorted and stored in ascending or descending on a particular key field. Records are organized in the sequence by which they were added.
3. Index file organization
Indexed Sequential file organization contains reference numbers, like employee numbers, that identify a record in relation to other records. It is logically the same as a sequential organization, but an index is built indicating the block containing the record with a given value for the Key field. An index is an alphabetical list of names, subjects, etc., with references to the places where they occur,
4. Random file organization
A randomly organized file is also called "direct file or direct access file" . It enables quick access to specific records. It contains records arranged physically without regard to the sequence of the primary key. Records are loaded to disk by establishing a direct relationship between the Key of the record and its address on the file, normally by use of a formula (or algorithm) that converts the primary Key to a physical disk address. This relationship is also used for retrieval.

CLASS ACTIVITIES

1. What is file organization?

2. Differentiate between sequential and random file organization.