FILE ORGANIZATION
Objective of this topic:
1.
To
know what file organization is
2.
The
type of file organization
3.
Important
of file organization
4.
The
factors to be considered when choosing file organization method.
Definition
of File: A file
is collection of data, usually stored on disk. As a logical entity, a file
enables you to divide your data into meaningful groups, for example, you can
use one file to hold at of a company's product information and another to hold
all of its personnel information. As a physical entity, a file should be
considered in terms of its 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.
Important
of file organization
1. Fast access to single record
or collection of related records.
2. Easy record
adding/update/removal, without disrupting
3. Storage efficiency.
4. Redundancy as a warranty
against data
Types
of file organization
1. Sequential
In a sequential file
organization, records 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.
2. Relative
Another type of organizing files
would be relative to the location where the file begins. A relative key is
assigned to determine the order of files. The first record would have a
relative number of 1; the second record would have a relative number of 2 and
so on. It is also called relative, because the sizes of each record unlike in a
sequential organization where the record sizes must be fixed to arrange
sequentially.
3. Indexed
An indexed file organization
contains reference numbers, like employee numbers, that identify a record in
relation to other records. These references are called the primary keys that
are unique to a particular record. Alternate keys can also be defined to allow
alternate methods of accessing the record. For example, instead of accessing a
record using employee numbers, you can use an alternate key that reference
employees by departments.
Factors to consider when choosing a file organization method.
There are several methods of file
organization and each one is suited for a particular task or purpose. Here are
the factors to consider before choosing a file organization method;
1.
Frequency
of update: A file that needs to be updated every now and then needs an
organization method that will allow easy retrieval of information and ease of
updating, example of such a file is the transaction file.
2.
File
activity: Different files have different activities, example a sort file is
used to sort data in Sequential order and therefore sequential method would be
appropriate for such a file.
3.
File
access method: Definitely different files have of being accessed; example a reference
file is accessed using random method for easy retrieval of data.
4.
Nature
of the system: Files that are used in a particular system will depend on the
nature of the system i.e. the suitable organization method for that particular
system.
5.
Master
file medium: The master file is the main file for keeping permanent updates of
records from transaction files and other sources, the medium by which it is
updated will determine the organization method to be used.