Data Storage Into File

File Processing

File processing is information processing in which
data ere stored independent file and each file is processed by different
application programmed. Such processing activities includes: performing some
calculations, sorting, merging etc.

The
Organization of Files

Recalled that file is a collection of related
records> each record holding a group of data. Each record in a file will
contain information about specific item that makes up the detailed information
being kept in the file. A file keeps information iii such away to allow for desired
processing.

File organization is the arrangement of records in
a file to allow desired processing in essence, organization of file can be
defined as the representation of stored records that makes up a file and it
shows the relationship the records.

There are 4 method of file organization, these are:

i.
Serial
files

ii.
Sequential
files

iii.
Direct/random
file

iv.
Indexed
sequential file.

Serial Files

Records on a serial file are arranged without
reference to a particular order. They are arranged as they occur. Also the records
in this file are accessed/retrieved the way they are organized. One may have to
go through the entire file to retrieve a record because there is no way
determines how many records may come after it. Assuming 1 have 10 records
namely R1, R2 — Rio assuming R3 is the First
to be available, will store it and so on

e.g.

R10

If you want to access any of these files you have
to go through the ones before retrieving it i.e. you has to pull out all file
before 1st you can set it.

Sequential Files

The records in a sequential file are stored in a
logical sequence accordingly. The records are normally organized in acceding
order of key field. It is the simplest file organization.

The arrangement of records is tape like. The records
in that file are accessed sequentially to extract a record with a given key;
all the preceding records in the file have to be accessed. E.g. assuming I have
10 records namely R1, R3 —— R10. The
records are arranged as follows:

R10

e.g. magnetic tape

There are some terms that are associated with this
kind of file. These are:

FIRST—-IN —- FIRST OUT (FIFO)

LAST—- IN —– LAST OUT (LILO)

Random/Direct Files

The individual records in these files are not
stored in any particular sequence of key fields, they are stored randomly. In
storing records in this file, it is necessary to develop on index which
indicates the location of each record. The recorder in a direct file has unique
addresses and each individual record can be accessed in approximately the same
period of time without having to search through other storage positions.

In essence, the arrangement of records in a direct
file, enable you to access data in a manner that is relatively independent of
the way the data are physically store. This method of file organization is
employed when a fast response is required from a file processing, e.g. hard
disk.

Index-Sequential
File

This is a file organization, that allows selective
records retrieval i.e. one can accessed a desired record without serial or
sequential searching through the file records.

An index-sequential file is loaded into a device
with the record in logical key order. As the file is loaded, it is indexed and
created. The indices show how the file is arranged on the device. Each index
shows which records are store on a part of the device.

There are 3 main ways in which an index-sequential
file can be processed:

1.
It can be
processed sequentially

2.
It can be
processed selective sequentially

3.
It can be
processed randomly.

Index-sequentially file organization is widely
applied to the storage of record on magnetic disk.

Note: File
organization on disc, They are four basic method of organizing file on disc.

1.
Serial

2.
Sequential

3.
Indexed
sequential

4.
Random.