What are the essential characteristics of a distributed database?

A distributed database is characterised by its data storage across multiple locations, concurrent accessibility, and synchronisation of data.

A distributed database system is a collection of multiple interconnected databases, which are spread physically across various locations that communicate via a data network. This means that the data is not stored in a central location but is distributed and stored across different sites, which could be spread across different cities or even countries. This distribution of data increases the reliability and availability of the data as it is not dependent on a single site.

One of the key characteristics of a distributed database is its concurrent accessibility. This means that the data can be accessed and modified simultaneously by multiple users without causing any conflicts. This is achieved through the use of sophisticated algorithms that ensure data consistency and integrity. For example, if two users are trying to book the same flight seat at the same time, the system will ensure that only one booking is successful.

Another important characteristic is the synchronisation of data. In a distributed database, changes made to the data at one site are reflected across all other sites. This ensures that all users have access to the most up-to-date data, regardless of where they are accessing it from. This is typically achieved through the use of a two-phase commit protocol, which ensures that all sites agree to a transaction before it is committed.

In addition, a distributed database is designed to be scalable. This means that as the volume of data or the number of users increases, the system can be easily expanded by adding more sites. This is a significant advantage over traditional databases, which can become overwhelmed as the volume of data increases.

Lastly, a distributed database provides a high level of transparency. This means that to the user, the distributed nature of the database is invisible. Users interact with the system as if it were a single, integrated database system, without needing to understand the complexities of the underlying distributed architecture. This makes distributed databases user-friendly and easy to interact with.