File Access Methods-R.D.Sivakumar

1. FILE ACCESS METHODS
Video Lecture and E-Content Created by
R.D.SIVAKUMAR,M.Sc.,M.Phil.,M.Tech.,
Assistant Professor of Computer Science &
Assistant Professor and Head, Department of M.Com.(CA),
Ayya Nadar Janaki Ammal College,
Sivakasi – 626 124.
Mobile: 099440-42243
e-mail : sivamsccsit@gmail.com website: www.rdsivakumar.blogspot.in

2. Files store information
The information in the file can be accessed in three ways
 Sequential Access
 Direct Access
 Indexed / Random Sequential Access
FILE ACCESS METHODS

3. Sequential access means that a group of elements (such as data in a memory array or
a disk file or on magnetic tape data storage) is accessed in a predetermined, ordered
sequence.
Sequential access is sometimes the only way of accessing the data, for example if it is
on a tape.
It may also be the access method of choice, for example if all that is wanted is to
process a sequence of data elements in order.
SEQUENTIAL ACCESS

4. Random access file organization provides, accessing the records
directly.
Each record has its own address on the file with by the help of which it
can be directly accessed for reading or writing.
The records need not be in any sequence within the file and they need
not be in adjacent locations on the storage medium.
DIRECT ACCESS

5. This mechanism is built up on base of sequential access.
An index is created for each file which contains pointers to various blocks.
Index is searched sequentially and its pointer is used to access the file
directly.
INDEXED SEQUENTIAL ACCESS