SS2 Second Term Data Processing Lesson Note – File Organization

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WEEK 2                                                                                

CLASS: SS 2                                                                        

TOPIC:  File Organization

CONTENT: 

1. Comparison of the Three file organization

SUB-TOPIC 1:         

FILE ORGANIZATION

File organization is a way of organizing the data or records in a file. It does not refer to how files are organized in folders, but how the contents of a file are added and accessed.

Is also a systematical way of arranging record in a file that is stored on a disk. You can access a file of record in different ways and tailor it in a variety of ways.

TYPES OF FILE ORGANIZATION

There are a large number of ways records can be organized on disk or tape. The main methods of file organization used for files are;

• Heap File Organization
• Sequential File Organization
• Hash / Direct File Organization
• Cluster File Organization
• Indexed Sequential Access Methods (ISAM)

Heap File Organization

An unordered file, sometimes called a heap file, is the simplest type of file organization.

Records are placed in file in the same order as they are inserted. A new record is inserted in the last page of the file; if there is insufficient space in the last page, a new page is added to the file. This makes insertion very efficient. However, as a heap file has no particular ordering with respect to field values, a linear search must be performed to access a record. A linear search involves reading pages from the file until the required is found.

Sequential File Organization:

In a sequential file organization, records are organized in the sequence by which they were added. You cannot insert a new record between existing records, but only at the end of the last record. It is a simple file organization that allows you to process batches of records in the file without adding or deleting anything. However, to access a particular record, processing must run through all the other records above it because it does not generate any random key to identify the location of the record.

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