How updates are processed

In a Dgraph cluster, updates to the records or configuration in a specific Dgraph database are routed to that database's leader Dgraph node.

The leader processes the update and commits it to the on-disk Dgraph database for the data set. It then informs the follower nodes that a new version of the Dgraph database is available. The leader Dgraph node and all follower Dgraph nodes can continue to use the previous version of the database to finish query processing that had started against that version.

As each Dgraph node finishes processing queries on the previous version, it releases references to it. Once the follower nodes are notified of the new version, they acquire read-only access to it and start using it.