1. A system, comprising: a plurality of database nodes that implement a distributed database; a common data store that persistently maintains data for the distributed database that is accessible to the plurality of database nodes; a read-only node of the plurality of database nodes, configured to: maintain in-memory system metadata that describes transaction state for a user transaction initiated at a read-write node of the plurality of database nodes; receive an indication of a change to the transaction state for the user transaction from the read-write node, wherein the initiated user transaction performs one or more updates to the data persistently maintained for the distributed database at the common data store; in response to the receipt of the indication of the change to the transaction state for the user transaction: update in-memory system metadata to apply the change to the transaction state for the user transaction in the in-memory system metadata; and make a view of the distributed database available for read requests according to the transaction state for the user transaction initiated at the read-write node.