Galera Cluster vs Patroni: What are the differences?

Introduction:

Galera Cluster and Patroni are both open-source tools used for managing database clusters, but they have key differences that make them suited for different use cases.

1. High Availability Mechanism: Galera Cluster utilizes a virtually synchronous replication method for ensuring high availability, which means that transactions are committed on all nodes before being considered complete. On the other hand, Patroni uses asynchronous replication and synchronous commit to achieve high availability, with transactions being sent to the primary node first then replicated to the replicas.

2. Supported Databases: Galera Cluster is primarily designed for MySQL and MariaDB databases, providing synchronous multi-master replication for them. In contrast, Patroni is targeted towards PostgreSQL databases, offering automated management and failover capabilities specifically for this database management system.

3. Configuration Management: Galera Cluster requires a complex configuration setup, including configuration files for each node and a shared configuration file. Patroni simplifies configuration management by using a single YAML configuration file that defines the cluster structure, replication settings, and failover parameters in an easily readable format.

4. Failover Handling: Galera Cluster relies on a built-in Quorum mechanism to handle failovers and prevent split-brain scenarios, ensuring data consistency across the cluster. Patroni utilizes leader election and consensus algorithms to manage failovers and elect a new primary node when the current one fails, providing automatic failover without the risk of conflicting writes.

5. Monitoring and Alerting: Galera Cluster lacks built-in monitoring and alerting features, requiring external tools for monitoring cluster health and performance. Patroni includes built-in monitoring capabilities through integration with tools like PgBouncer and Prometheus, offering real-time insights into cluster status and performance metrics.

6. Client Connectivity: Galera Cluster supports client connections to any node in the cluster, allowing read and write operations on any node. In contrast, Patroni restricts client connections to the primary node for write operations, while read operations can be distributed among all nodes in the cluster.

In Summary, Galera Cluster and Patroni differ in high availability mechanisms, supported databases, configuration management, failover handling, monitoring capabilities, and client connectivity preferences.