Migrating to v3.9 HA
Memgraph 3.9 includes a fix for a bug in how durability is handled on coordinators in a high-availability (HA) setup. Because of this fix, all coordinator data directories must be cleaned and coordinators must be started fresh.
Data instances are not affected and can stay unchanged.
Upgrading to 3.9 cannot be performed without downtime if you are using a routing connection to connect to the currently writable instance. You can, however, keep using direct Bolt connections to data instances during this maintenance period.
Clean coordinator data directories
Remove the data directories of all coordinators. If you are running Memgraph HA in Kubernetes, delete the coordinators’ PVCs and PVs before the restart.
Restart coordinators
Start all coordinators with the new Memgraph 3.9 version.
Reconnect the cluster
After the coordinators are running, reconnect your cluster by executing
REGISTER INSTANCE and ADD COORDINATOR queries for each data instance and
coordinator respectively.