Database Replication

What is Database Replication? 

Database replication is the process of creating and maintaining multiple copies of a database across different physical or logical locations. 

It involves copying data from a source database, known as the master or primary database, to one or more destination databases. These copies are secondary databases or replicas. Database replication plays a vital role in ensuring data redundancy, high availability, and disaster recovery.

Database replication ensures that changes made to the master database are propagated to all replicas. The data has to be consistent and up to date across the entire system.

Benefits of Database Replication

High Availability

Replication enhances system availability by creating redundant copies of the database. The master database may become unavailable due to hardware failure, network issues. In that case one of the replicas can seamlessly take over, minimizing downtime and ensuring continuous access to data.

Load Balancing

By distributing read operations across multiple replicas, database replication enables efficient load balancing. This helps lower the load on the master database, improves system performance, and provides a better experience for end-users.

Disaster Recovery

Replication acts as a crucial component of disaster recovery strategies. There might be a catastrophic failure or data corruption in the master database. If that happens replicas can be utilized to quickly restore the system to a consistent state, minimizing data loss and downtime.

Geographic Distribution

Replicating databases across the globe allows organizations to serve users from different regions more effectively. By placing replicas closer to users, latency is reduced, resulting in improved response times and better user experiences.

Common Database Replication Methods

There are many methodologies for database replication. The application depends on the use case and size of the database. These are the principal methods: 

Snapshot Replication

In this method, a snapshot of the master database is taken at regular intervals and transferred to the replicas. Each snapshot contains the entire database state. There are no updates till the next replication. Although simple to implement, snapshot replication can be resource-intensive if the database is large. 

Transactional Replication

Transactional replication tracks individual database transactions on the master and replicates them to the replicas in near real-time. This method ensures that each transaction is applied to the replicas in the same order as on the master, maintaining data consistency.

Merge Replication

Merge replication is typically employed in distributed systems with multiple masters that can update the database independently. Each replica maintains its copy of the database and periodically synchronizes with other replicas.