Comparison of Centralized and Distributed Database with advantages disadvantages

Comparison of Centralized and Distributed Database with advantages disadvantages

Centralized database

In a centralized database, all data is stored and maintained in one place. The central location is a computer or database. All the data is stored in a single location for example mainframe computer.

This database mostly maintains and modify using internet connection like LAN and WAN.

The centralized database mostly used in colleges, banks, hospitals and in small companies. In a centralized database system one computer act as a server for storing whole data. In a centralized database system, client/server architecture is used it is the very simplest form of a database system in which one client sent a request to the server. The server will receive a request and will be the response. Many small organizations use a centralized database system.

In the above diagram all the data stored on a single computer. This database is known as the centralized database.

Characteristics of a Centralized System

  • Presence of a global clock:

As the whole system consists of a central computer (a server/ a master) and many client computers (a computer/ a slave), all client nodes connect up with the global clock(the clock of the central node).

  • One single central unit:

The central server will communicate with all clients. All client sends a request to server and server will be the response.

  • Dependent failure of components:

When the server goes down all system will be destroyed. The client is not able to access the database

Advantages of  Centralized Database Management System

Some advantages of a Centralized Database Management System are:

  1. The integrity of data is increased as the whole database is stored at a single physical location. In this way, it is easy to manage the data is most consistent and accurate in this way.
  2. The data redundancy is controlled in a centralized database. All the data is stored in one location and it cannot distribute on different places. So, it is easier to make sure all the datastore is not duplicate. in this way redundancy easily control
  3. The centralized database is much secure. Because all data is stored in one place
  4. Data is easily portable because it is stored in the same place. Strong data security
  5. The centralized database is inexpensive than other databases .it required less expense on maintains
  6. All the information is easily accessible. it takes less time to get the required information from a centralized database

Disadvantages Centralized Database Management System

Some disadvantages of a Centralized Database Management System are:

  1. If the network is slow, the accessibility of required because all data is stored in one place.Since all the data is at one location. The searching process takes much time.
  2. If the centralized server fails due to some reasons all database will be a loss.
  3. All data is stored in one place when many users access data at the same time to may create many problems.
  4. When the many record same place will be accessed at the same time the collision will be accord in the result of collision may be precious data will be lost.

Distributed Database

In the distributed database all clients are not attached with common server computer. The data is stored on a different computer located in the same physical location. The database is distributed over the network. Collection of data can be distributed over many physical places.it improves overall performance. However, rely on a central DBMS which manages all its different storage devices remotely, as it is not necessary for them to be kept in the same physical and/or geographical location.

Characteristics Distributed or decentralized database System

Lack of a global clock:

Every node works independently from each other, have different clocks that they run and follow.

Multiple central units (Computers/Nodes/Servers):

More than one central unit which can listen for connections from other nodes

Dependent failure of components:

One central node failure does not destroy the whole system.

 

Components of Distributed database System

Components of Distributed database System are,

  • Node (Computer, Mobile, etc.)
  • A communication link

Advantages of Decentralized System –

    1. The performance of the distributed database is very high because all load is divide over all nodes.
    2. All the nodes available for work, leading to high availability
    3. More autonomy and control over resources .because each node controls its own work, it has better autonomy leading to more control over resources

Disadvantages of Decentralized System –

  1. It is very difficult to use because it is very large and complex.
  2. When one node becomes fail it is very difficult to detect because there are many nodes and responsible for their own behavior
  3. The server accepts request from nodes in the system but it is actually difficult to find out which node indeed served the request.

Comparison of Distributed and Centralized Database System

Centralized Database Distributed Database
A type of database in which all data stored on the central device. Central device may be a mobile or a computer etc. A type of database that consists of two or more database files located at different places over the network.
Managing, modifying and backup of data is easy because all data stored in one place. As there are multiple database files, in a distributed database, it requires time to manage data.
Requires time to access data because multiple users access the database files. It has good speed in accessing data because data files are retrieved from the nearest database.
If the central server fails users are not able to access database If one database fails user still access another database
Has more data consistency and it provides the complete user view May have data replication and there can be some data inconsistency.

 

Prof. Fazal Rehman Shamil
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