Galera Cluster vs PostgreSQL: What are the differences?

Introduction

Galera Cluster and PostgreSQL are both popular options for managing and organizing databases. However, they have some key differences that set them apart. In this article, we will explore the main variations between Galera Cluster and PostgreSQL.

1. Scalability: Galera Cluster is a distributed multi-master database system, allowing it to provide high availability and scalability. It allows for synchronous replication, meaning all nodes are kept in sync at all times. On the other hand, PostgreSQL is a traditional RDBMS that offers asynchronous replication, which can create some latency and delay in data propagation.

2. Architecture: Galera Cluster is based on a plugin for the MariaDB and MySQL databases. It uses the write-set replication method to achieve synchronous replication. PostgreSQL, on the other hand, follows a master-slave replication model, where a single master node handles writes, and slave nodes replicate data from the master asynchronously.

3. Conflict Resolution: With Galera Cluster, when conflicting operations occur on different nodes, they are automatically resolved based on a strict quorum model. This means that only a single version of a row will be considered valid across all nodes. In PostgreSQL, conflict resolution is performed manually, requiring developers to handle and resolve conflicts themselves.

4. Compatibility: Galera Cluster continues to be closely tied to the MySQL and MariaDB databases, relying on their syntax and features. PostgreSQL, on the other hand, is an independent and feature-rich database system that follows the SQL standard more strictly.

5. Replication Delay: Due to its synchronous replication, Galera Cluster ensures that all nodes have identical data at all times. This eliminates data discrepancies but may introduce some latency and potential performance impact. PostgreSQL's asynchronous replication allows for greater flexibility and potentially lower replication delay, but it can result in data inconsistencies during failover.

6. Flexibility: Galera Cluster's multi-master architecture allows for reads and writes to happen on any node, providing better load balancing and high availability. PostgreSQL, being a master-slave system, requires all writes to go through the master node, which can become a bottleneck in high-write environments.

In summary, Galera Cluster provides a high level of availability and scalability with synchronous replication, automatic conflict resolution, and multi-master capabilities. PostgreSQL, on the other hand, offers more flexibility and compatibility as an independent database system with asynchronous replication and manual conflict resolution.