Google was granted a new patent: "Systems and methods for performing record append operations". The abstract of the patent:
"A system facilitates the performance of a record append operation. The system may include a primary replica and one or more secondary replicas that store copies of data. The primary and secondary replicas may receive a record to be appended to the data and a record append request that identifies the record to be appended to the data. The primary and secondary replicas may append the record to the data, possibly at the same offset. If multiple record append requests are concurrently received, the requests may be serialized to establish an order for the requests."
This patent is used for Google's distributed file system, "that delivers good scalable aggregate performance and continued operation in the event of failures". The idea here is that more than one computer can append data to a file in an easy way. Google uses more than one backup for their data, so that a disk failure doesn't make some files inaccessible. Appending data to a file concurrently means replicating the file changes in a consistent way.
Google File System patent