Designing MySQL Replication Topologies That Actually Work

Replication Is Simple Until It Is Not

MySQL replication is deceptively easy to set up and remarkably easy to get wrong at scale. A basic source-replica configuration takes minutes. A topology that handles failover gracefully, maintains consistency, and scales reads without creating operational nightmares takes careful planning.

Choosing Your Replication Mode

Asynchronous replication is the default and fastest, but it risks data loss during failover. Semi-synchronous replication guarantees at least one replica has the transaction, at the cost of some write latency. Group Replication provides consensus-based replication with automatic conflict detection. The right choice depends on your consistency requirements and latency tolerance.

GTID-Based Replication Is Non-Negotiable

If you are still using file-position based replication, you are making failover harder than it needs to be. GTID-based replication simplifies topology changes, makes point-in-time recovery more reliable, and is required for tools like Orchestrator and InnoDB Cluster to function properly.

Plan your topology for the failure scenarios you will inevitably face, not just the steady-state operations that work fine today.