Database, Database Management System, Types of database Distributed database,

1. DISTRIBUTED DATABASE SYSTEM
By
M. AHMAD MAHMOOD

2. Database
 A database is a collection of information that is organized so that it can be easily accessed,
managed and updated.
 Data is organized into rows, columns and tables, and it is indexed to make it easier to find
relevant information.
 Data gets updated, expanded and deleted as new information is added. Databases process
workloads to create and update themselves, querying the data they contain and running
applications against it.

3. Database Management System (DBMS)
 A database management system (DBMS) is system software for creating and
managing databases.
 The DBMS provides users and programmers with a systematic way to create, retrieve, update and
manage data.

4. Types of Data Base
There are three types Data Base Systems:
1. Centralized Data Base System.
2. Distributed Data Base System.
3. Decentralized Data Base System.

5. Centralized database
 A centralized database holds all data on a central computer such as a mainframe
computer or server.

6. Distributed Database
 A distributed database is a database in which portions of the database are stored on
multiple computers within a network.

7. Decentralized Database
 The user would have to connect to the network and they will have access to the
site that is connected to the user’s computer.

8. Advantages of DDBS
 Reliability, if one of the sites crashes, the system will keep running with the other sites.
 Speed, it is faster because the information is distribute and not packed as a whole.
 Open system, the system could connect to other networks to make it bigger and accessible
everywhere.

9. Disadvantages of DDBS
 Open system, the system could connect to other networks to make it bigger and accessible
everywhere.
 Proper hardware and software, the database needs proper hardware and software to run
properly, this is expensive to get.
 Troubleshooting, there might be connection error that could affect the use of the database by
other users.

10. Basic Differences b/w Databases
DecentralizedDistributed DatabaseCentralized Database
Centralized database have
a central computer.
The distributed database
has several central
computers.
Decentralized database are
separated and have
different central computers.