Database File System in DBMS, File Management

Module I – Session 2
Database, File system,
DBMS
●
File System
●
Database
●
Database Management
System
Presented by
Dr.S.Zulaikha Beevi,
Professor/CSE

Files
●
A file represents a sequence of bytes on the disk
where a group of related data is stored.
●
File is created for permanent storage of data.
#include<stdio.h>
struct emp
{
char name[10];
int age;
};
void main()
{
struct emp e;
FILE *p,*q;
p =
fopen("one.tx
t", "a");
q = fopen("one.txt", "r");
printf("Enter Name and Age:");
scanf("%s %d", e.name, &e.age);
fprintf(p,"%s %d", e.name, e.age);
fclose(p);
do
{
fscanf(q,"%s %d", e.name,
e.age);
printf("%s %d", e.name,
e.age);
}
while(!feof(q));
}

File System to
DBMS
File System manages data using files in hard disk. Users
are allowed to create, delete, and update the files
according to their requirement.
Let us consider the example of file based University
Management System. Data of students is available to their
respective Departments, Academics Section, Result
Section, Accounts Section, Hostel Office etc. Some of the
data is common for all sections like Roll No, Name, Father
Name, Address and Phone number of students but some
data is available to a particular section only like Hostel
allotment number which is a part of hostel office.

Issues in File
System
Redundancy of data: Data is said to be redundant if
same data is copied at many places. If a student wants
to change Phone number, he has to get it updated at
various sections. Similarly, old records must be deleted
from all sections representing that student.
Inconsistency of Data: Data is said to be inconsistent if
multiple copies of same data does not match with each
other. If Phone number is different in Accounts Section
and Academics Section, it will be inconsistent.
Inconsistency may be because of typing errors or not
updating all copies of same data.

Difficult Data Access: A user should know the exact
location of file to access data, so the process is very
cumbersome and tedious. If user wants to search
student hostel allotment number of a student from
10000 unsorted students’ records, how difficult it can be.
Unauthorized Access: File System may lead to
unauthorized access to data. If a student gets access to
file having his marks, he can change it in unauthorized
way.
No Concurrent Access: The access of same data by
multiple users at same time is known as concurrency. File
system does not allow concurrency as data can be
accessed by only one user at a time.
No Backup and Recovery: File system does not
incorporate any backup and recovery of data if a file is
lost or corrupted.

Database
Database is a collection of inter-related data
which helps in efficient retrieval, insertion and
deletion of data from database and organizes
the data in the form of tables, views, schemas,
reports etc.
For Example, university database organizes
the data about students, faculty, and admin
staff etc. which helps in efficient retrieval,
insertion and deletion of data from it.

Database
Architecture
•Centralized databases
• One to a few cores, shared memory
•Client-server,
• One server machine executes work
on behalf of multiple client
machines.
•Parallel databases
• Many core shared memory
• Shared disk
• Shared nothing
•Distributed databases
• Geographical distribution
• Schema/data heterogeneity

Database File System in DBMS, File Management

Database Management System
The software which is used to manage database is
called Database Management System (DBMS).
For Example, MySQL, Oracle etc. are popular
commercial DBMS used in different applications.
DBMS allows users the following tasks:
Data Definition: It helps in creation, modification and
removal of definitions that define the organization of data
in database.

Data Updation: It helps in insertion, modification
and deletion of the actual data in the database.
Data Retrieval: It helps in retrieval of data from the
database which can be used by applications for
various purposes.
User Administration: It helps in registering and
monitoring users, enforcing data security, monitoring
performance, maintaining data integrity, dealing with
concurrency control and recovering information
corrupted by unexpected failure.

Advantages of
DBMS
DBMS helps in efficient organization of data in database which has following advantages over
typical file system.
Minimized redundancy and data consistency: Data is normalized in DBMS to minimize the
redundancy which helps in keeping data consistent. For Example, student information can be
kept at one place in DBMS and accessed by different users.
Simplified Data Access: A user need only name of the relation not exact location to access
data, so the process is very simple.
Multiple data views: Different views of same data can be created to cater the needs of different
users. For Example, faculty salary information can be hidden from student view of data but
shown in admin view.
Data Security: Only authorized users are allowed to access the data in DBMS. Also, data can
be encrypted by DBMS which makes it secure.
Concurrent access to data: Data can be accessed concurrently by different users at same time
in DBMS.
Backup and Recovery mechanism: DBMS backup and recovery mechanism helps to avoid
data loss and data inconsistency in case of catastrophic failures.

Need for
DBMS
A Data Base Management System is a system software
for easy, efficient and reliable data processing and
management. It can be used for:
●
Creation of a database.
●
Retrieval of information from the database.
●
Updating the database.
●
Managing a database.

Qui
z
1. What is database?
A. Collection of organized data that allows access,
retrieval of that data.
B. Collection of organized data that allows access,
retrieval, and use of that data.
C. Collection of organized data that allows retrieval, and
use of that data.
Answer : B

Database File System in DBMS, File Management

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