US Patent 9747320 Efficient reference counting in content addressable storage

A process manages database storage. The process receives a first object comprising one or more content chunks. The first object is identified by a unique object ID and each content chunk has a unique offset within the first object. For each chunk, the process inserts a record into a reference table. The record includes a content hash and the object ID. The process stores each of the chunks in content storage. Later, the process obtains a request to delete a first chunk from storage. The first chunk has a corresponding first content hash. The process determines whether the reference table includes a reference record corresponding to the first content hash. When the reference table does not include any reference records corresponding to the first content hash, the process deletes the first chunk. When the reference table includes a corresponding reference record, the process does not delete the first chunk.