Database Replication

Database replication is a technique in which data from a database is copied (replicated) from one database (master) to another database (replica) to keep the replica database synchronized with the master database. This process can be done in real-time or at scheduled intervals.

The main purpose of database replication is to ensure data availability and consistency across different geographical and network locations. It also helps in load balancing by allowing read operations to be distributed across multiple nodes.

There are several types of database replication, including:

1. Master-Slave Replication: In this type, one database server maintains the master database and the rest of the database servers maintain the slave databases. All data modification operations (INSERT, UPDATE, DELETE) are performed on the master database and then replicated to the slave databases.

2. Multi-Master Replication: In this type, two or more database servers maintain the same database. Any changes made to any server are replicated to all other servers. This type of replication is more complex but provides a higher level of availability.

3. Snapshot Replication: In this type, the entire database is copied from the master to the slave at scheduled intervals. This is a simple form of replication but can be resource-intensive for large databases.

4. Transactional Replication: In this type, only the changes (transactions) made at the master database are sent to the slave databases. This is more efficient than snapshot replication for databases where changes are relatively infrequent.

5. Merge Replication: In this type, changes can be made to both the master and slave databases and the changes are merged together. This is useful for distributed databases where network connectivity cannot be guaranteed.

Remember, the choice of replication strategy depends on the specific requirements of your application, including the need for data availability, consistency, network bandwidth, and system performance.