Database develop. life cycle - Distributed Database Concepts

A distributed database is a database in which data is stored across multiple physical locations but appears to users as a single unified database system. These locations may be in the same building, different cities, or even different countries. Distributed databases are designed to improve availability, scalability, reliability, and performance of large-scale systems.

Characteristics of Distributed Databases

One important characteristic is data distribution, where data is divided and stored across different nodes. Users are not aware of where the data is physically stored, which provides location transparency. Another key feature is autonomy, meaning each site can operate independently while still being part of the global system.

Distributed databases also provide fault tolerance. If one node fails, the system continues to function using other nodes. This makes distributed databases highly reliable compared to centralized databases.

Data Distribution Techniques

There are two major data distribution techniques:

Replication

Replication involves storing copies of the same data at multiple locations. This improves data availability and read performance. However, it increases complexity in maintaining data consistency when updates occur.

Fragmentation (Sharding)

Fragmentation divides a database into smaller pieces called fragments or shards. Each fragment contains a subset of data. Fragmentation can be horizontal (rows), vertical (columns), or mixed. Sharding improves performance by distributing workload across servers.

CAP Theorem

The CAP theorem states that a distributed database can satisfy only two of the following three properties at the same time:

  • Consistency – all users see the same data

  • Availability – system always responds to requests

  • Partition tolerance – system works even if communication fails

This theorem helps designers choose the right trade-offs based on application requirements.

Advantages of Distributed Databases

Distributed databases provide high availability, better performance, scalability, and improved reliability. They are ideal for cloud-based and global applications.

Challenges of Distributed Databases

 

Despite benefits, distributed databases face challenges such as complex management, data consistency issues, network latency, and security risks. Proper design and coordination are required to manage these challenges.