How MySQL Router 8.2 Enables Seamless Read/Write Splitting with InnoDB ReplicaSet

MySQL InnoDB ReplicaSet

This section introduces the simplest InnoDB ReplicaSet architecture, consisting of a single source instance and one or more asynchronous replicas.

The ReplicaSet object status can be viewed in MySQL Shell.

Starting MySQL Router 8.2

Configure and launch MySQL Router to enable read/write splitting.

The Router appears in the ReplicaSet object within MySQL Shell.

Connecting to MySQL via the read/write port (6450) demonstrates that read operations are automatically directed to a replica, while write operations go to the primary source without changing the connection parameters.

When a transaction is started, the connection switches to the source instance, while plain reads continue to use the replica.

The generated read/write split configuration appears in the Router's configuration file:

[routing:bootstrap_rw_split]
bind_address=0.0.0.0
bind_port=6450
destinations=metadata-cache://myreplica/?role=PRIMARY_AND_SECONDARY
routing_strategy=round-robin
protocol=classic
connection_sharing=1
client_ssl_mode=PREFERRED
server_ssl_mode=PREFERRED
access_mode=auto

Session-level control is possible with the ROUTER SET access_mode= command to specify which instance type to use.

Conclusion

MySQL Router 8.2 fully supports read/write splitting for InnoDB ReplicaSet clusters, allowing all read traffic to be routed to read‑only replicas and all write traffic to the primary instance without any application changes. This feature improves database performance, scalability, and simplifies deployment and management.