Data updates in distributed system with data coherency

An apparatus comprising:

• a storage device that stores a distributed database in a distributed system, the distributed database to store a data element, the distributed system having a network of multiple nodes that store a copy of the data element, each node coupled to, and in communication with, the data coordinator;
• and
• a data coordinator to
• receive a request to modify the data element of the distributed system,
• lock the data element at the device to prevent access to the data element in response to receiving the proposed change,
• send, after locking the data element at the device, an invalidation of the data element to the nodes of the distributed system storing a copy of the data element to invalidate copies of the data element stored at the nodes,
• receive by the device zero or more acknowledgements of the invalidation by the nodes storing a copy of the data element,
• update the data element in accordance with the requested modification if all nodes in the distributed system storing a copy of the data element acknowledge the invalidation of the data element, otherwise, terminate the requested modification to the data element to prevent the proposed change from being made, including maintaining an unchanged value of the data element, wherein the updating the data element if all nodes acknowledge the invalidation otherwise terminating the proposed change prevents valid data from becoming inconsistent across the nodes, the updated or unchanged data element then being a current, valid value of the data element in the database, and
• unlock the data element after either updating the data element or terminating the proposed change to the data element to make the data element available for access.

An article of manufacture comprising a computer-readable storage medium having instructions stored thereon, which when executed, cause a processor to:

• receive at a device incorporating a data coordinator a proposed change to a data element of a distributed system, the distributed system having multiple nodes storing a copy of the data element, each node coupled to, and in communication with, the data coordinator;
• lock the data element at the device to prevent access to the data element in response to receiving the proposed change;
• send, after locking the data element at the device, an invalidation of the data element to the nodes of the distributed system storing a copy of the data element to invalidate copies of the data element stored at the nodes;
• receive by the device zero or more acknowledgements of the invalidation by the nodes storing a copy of the data element;
• update the data element in accordance with the proposed change if all nodes in the distributed system storing a copy of the data element acknowledge the invalidation of the data element, otherwise,
• terminate the proposed change to the data element to prevent the proposed change from being made, including maintaining an unchanged value of the data element, wherein the updating the data element if all nodes acknowledge the invalidation otherwise terminating the proposed change prevents valid data from becoming inconsistent across the nodes,
• the updated or unchanged data element then being a current, valid value of the data element;
• and
• unlock the data element after either updating the data element or terminating the proposed change to the data element to allow access to the data element.