Galera Cluster vs MariaDB: What are the differences?

Introduction

Galera Cluster and MariaDB are both open-source database management systems that offer high availability and scalability features. However, there are several key differences between these two technologies.

1. Data Replication: Galera Cluster uses synchronous multi-master replication, which means that all nodes in the cluster are actively involved in the replication process and can accept write operations. On the other hand, MariaDB uses asynchronous master-slave replication, where write operations are performed on the master node and then asynchronously propagated to the slave nodes. This difference in replication methodologies can affect the consistency and performance of the database.

2. Conflict Resolution: In Galera Cluster, conflicts that occur when two or more nodes attempt to modify the same piece of data are resolved automatically by the built-in conflict detection and resolution mechanism. MariaDB, on the other hand, does not have an automatic conflict resolution mechanism, and conflicts need to be resolved manually or through custom coding. This difference simplifies application development and enhances data consistency in Galera Cluster.

3. Cluster Size Limit: Galera Cluster has a limitation on the maximum number of nodes that can be part of a cluster. By default, the maximum cluster size in Galera is 9 nodes, but this can be increased by modifying configuration settings. On the contrary, MariaDB does not have a strict limit on the number of nodes in a cluster, allowing for greater scalability and flexibility in larger deployments.

4. Write Scalability: Galera Cluster offers true multi-master write scalability, where write operations can be distributed across all nodes in the cluster. This means that the write capacity of the cluster can be increased linearly by adding more nodes. In contrast, MariaDB's master-slave replication model limits write scalability as all write operations are performed on a single master node. Additional slave nodes can be used to offload read operations, but write operations are still limited by the capacity of the master node.

5. Conflict Prevention: Galera Cluster includes a feature called "Certification-Based Replication" that prevents most conflicts from occurring in the first place. This feature uses a "first committer wins" approach to ensure that only the node that commits a transaction first will have its changes propagated to the other nodes. MariaDB does not have a built-in conflict prevention mechanism, increasing the chances of conflicts occurring and potentially causing data inconsistencies.

6. Network Requirements: Galera Cluster relies on a high-speed and low-latency network to maintain synchronous replication between nodes. The network latency between nodes should be below a certain threshold to ensure optimal performance and consistency. On the other hand, MariaDB's asynchronous replication is less dependent on network latency and can handle higher latencies without significantly affecting performance. This difference in network requirements makes Galera Cluster more suitable for deployments with more reliable and low-latency networks.

In summary, the key differences between Galera Cluster and MariaDB lie in their replication methodologies, conflict resolution mechanisms, cluster size limits, write scalability, conflict prevention, and network requirements. Galera Cluster offers synchronous multi-master replication, automatic conflict resolution, a maximum cluster size limitation, true multi-master write scalability, conflict prevention, and high network requirements. On the other hand, MariaDB uses asynchronous master-slave replication, manual conflict resolution, no strict cluster size limit, limited write scalability, no conflict prevention, and lower network requirements.