ADVANTAGES OF DBMS
One of the major advantages of using a database system is that the organization
can be handled easily and have centralized management and control over the data by
the DBA. Some more and main advantages of database management system are given
below:
The main advantages of DBMS are:
1. Controlling Redundancy
In a DBMS there is no redundancy (duplicate data). If any type of
duplicate data arises, then DBA can control and arrange data in
non-redundant way. It stores the data on the basis of a primary key,
which is always unique key and have non-redundant information. For
example, Roll no is the primary key to store the student data.
In
traditional file processing, every user group maintains its own files.
Each group independently keeps files on their db e.g., students.
Therefore, much of the data is stored twice or more. Redundancy leads to
several problems:
• Duplication of effort
• Storage space wasted when the same data is stored repeatedly
Files that represent the same data may become inconsistent (since
the updates are applied independently by each users group).We can use
controlled redundancy.
2. Restricting Unauthorized Access
A DBMS should provide a security and authorization subsystem.
• Some db users will not be authorized to access all information in the db (e.g., financial data).
• Some users are allowed only to retrieve data.
• Some users are allowed both to retrieve and to update database.
3. Providing Persistent Storage for Program Objects and Data Structures
Data structure provided by DBMS must be compatible with the
programming language’s data structures. E.g., object oriented DBMS are
compatible with programming languages such as C++, SMALL TALK, and the
DBMS software automatically performs conversions between programming
data structure and file formats.
4. Permitting Inferencing and Actions Using Deduction Rules
Deductive database systems provide capabilities for defining
deduction rules for inferencing new information from the stored database
facts.
5. Inconsistency can be reduced
In a database system to some extent data is stored in, inconsistent
way. Inconsistency is another form of delicacy. Suppose that an em1oyee
“Japneet” work in department “Computer” is represented by two distinct
entries in a database. So way inconsistent data is stored and DBA can
remove this inconsistent data by using DBMS.
6. Data can be shared
In a database system data can be easily shared by different users.
For example, student data can be share by teacher department,
administrative block, accounts branch arid laboratory etc.
7. Standard can be enforced or maintained
By using database system, standard can be maintained in an
organization. DBA is overall controller of database system. Database is
manually computed, but when DBA uses a DBMS and enter the data in
computer, then standard can be enforced or maintained by using the
computerized system.
8. Security can be maintained
Passwords can be applied in a database system or file can be
secured by DBA. Also in a database system, there are different coding
techniques to code the data i.e. safe the data from unauthorized access.
Also it provides login facility to use for securing and saving the data
either by accidental threat or by intentional threat. Same recovery
procedure can be also maintained to access the data by using the DBMS
facility.
9. Integrity can be maintained
In a database system, data can be written or stored in integrated
way. Integration means unification and sequencing of data. In other
words it can be defined as “the data contained in the data base is both
accurate and consistent”. ‘Data can be accessed if it is
compiled
in a unique form. We can take primary key ad some secondary key for
integration of data. Centralized control can also ensure that adequate
checks are
incorporated in the DBMS to provide data integrity.
10. Confliction can be removed
In a database system, data can be written or arranged in a
well-defined manner by DBA. So there is no confliction between the
databases. DBA select the best file structure and accessing strategy to
get better performance for the representation and use of the
data.
11. Providing Multiple User Interfaces
For example query languages, programming languages interfaces, forms, menu- driven interfaces, etc.
12. Representing Complex Relationships Among Data
It is used to represent Complex Relationships Among Data
13. Providing Backup and Recovery
The DBMS also provides back up and recovery features.
DISADVANTAGES OF DBMS
Database management system has many advantages, but due to some major problem
arise in using the DBMS, it has some disadvantages. These are explained as:
1.Cost
A significant disadvantage of DBMS is cost. In addition to the cost
of purchasing or developing the software, the organization *111 also
purchase or upgrade the hardware
and so it becomes a costly system. Also additional cost occurs due to migration of data
from one environment of DBMS to another environment.
2. Problems associated with centralization
Centralization also means that data is accessible from a single
source. As we know the centralized data can be accessed by each user, so
there is no security of data from unauthorized access and data can be
damaged or lost.
3. Complexity of backup and recovery
Backup and recovery are fairly complex in DBMS environment. As in a
DBMS, if you take a backup of the data then it may affect the
multi-user database system which is in operation. Damage database can be
recovered from the backup floppy, but iterate duplicacy in loading to
the concurrent multi-user database system.
4. Confidentiality, Privacy and Security
When information is centralized and is made available to users from
remote locations, the possibilities of abuse are often more than in a
conventional system. To reduce the chances of unauthorized users
accessing sensitive information, it is necessary to take technical,
administrative and, possibly, legal measures. Most, databases store
valuable information that must be protected against deliberate trespass
and destruction.
5. Data Quality
Since the database is accessible to users remotely, adequate
controls are needed to control users updating data and to control data
quality. With increased number of users accessing data directly, there
are enormous opportunities for users to damage the data. Unless there
are suitable controls, the data quality may be compromised.
6. Data Integrity
Since a large number of users could be using .a database
concurrently, technical safeguards are necessary to ensure that the data
remain correct during operation. The main threat to data integrity
comes from several different users attempting to update the same data at
the same time. The database therefore needs to be protected against
inadvertent changes by the users.
7. Enterprise Vulnerability
Centralizing all data of an enterprise in one database may mean
that the database becomes an indispensable resource. The survival of the
enterprise may depend on reliable information being available from its
database. The enterprise therefore becomes vulnerable to the destruction
of the database or to unauthorized modification of the database.
8. The Cost of using a DBMS
Conventional data processing systems are typically designed to run a
number of well-defined, preplanned processes. Such systems are often
“tuned” to run efficiently for the processes that they were designed
for. Although the conventional systems are usually fairly inflexible in
that new applications may be difficult to implement and/or expensive to
run, they are usually very efficient for the applications they are
designed for.
The database approach on the other hand provides a flexible
alternative where new applications can be developed relatively
inexpensively. The flexible approach is not without its costs and one of
these costs is the additional cost of running applications that the
conventional system was designed for. Using standardized software is
almost always less machine efficient than specialized software.
Q. 8. List five significant differences between a file-processing system and a DBMS.
Ans. Before
differentiating between file and database systems, there be need to
understand the DBMS and its component. Let us consider an organization
have a huge amount (collection) of data on its different departments,
its employees, its products, sale and purchase order etc. As we know
such type of data is accessed simultaneously by different and several
employees. Now some users apply number of queries and want answers
quickly. If data is stored in the files, then it will create a problem
of slow processing. As we try to deal with this type of data management
problem by storing the data in a collection of operating system files.
Such type of techniques creates number of problems or drawbacks, which
are discussed as below:
1.
As we have not 1000GB main memory (primary memory) to store the data,
so we store the data in some permanent storage device
(secondary memory) like magnetic disk or magnetic tape etc. So
file-oriented system fails in primary memory cases and we apply data
base management system to store the data files permanently.
2.
Suppose if we have such a large amount of primary memory on a 16 bit or
32 bit computer system, then there be a problem occur in file based
system to use the data by direct or random addressing. Also we cannot
call more then 2GB or 4Gb of data direct to the primary memory at a
time. So there be need a database program to identify the data.
3.
Some programs are too lengthy and complex which cannot store large
amount of data in the files related to the operating systems. But a
database system made it simple and fast.
4.
We cannot change and access file-oriented data simultaneously, so we
have requirement a type of system which can be used to access the large
amount of data concurrently.
5. Also we cannot recall or recover the file-oriented data, but centralized database management solve such type of problem.
6.
File oriented operating system provide only a password mechanism for
security, but this is not successful in case of number of users are
accessing the same data by using the same login.
At end we can sat that a DBMS is a piece of software that is designed to make the processing faster and easier.
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