Distributed Database - Introduction

What is Distributed Database? / Types of Distributed Databases / Homogeneous and Heterogeneous Distributed Databases

 
What is Distributed Database?

A database which is distributed over some form of network to bring down the cost or the difficulty in accessing data and to increase the efficiency of the whole system.

Types of Distributed Databases

1. Homogeneous Distributed Database

• Identical software are  used in all the sites

• Here, a site refers to a server which is part of the distributed database system 
• Software would mean OS, DBMS software, and even the structure of the database used
• In some cases, identical hardware are also used

• All sites are well known. 
•  As they are similar in terms of DBMS software and hardware used

• Partial control over the data of other sites 
  • As we know the structure of databases, software and hardware used in other sites. Hence the partial control over the data is possible
• Looks like a single central database system  

 

2. Heterogeneous Distributed Database 

• Different sites uses different database software
• The structure of databases reside in different sites may be different (because of data partitions)
• Co-operation between sites are limited. That is, it is not easy to alter the structure of the database or any other software used