In order to improve interactive compression using compression state information, the side information caches of communicating parties must be updated, or synchronized. The present invention is directed to a method of synchronizing side information databases within an interactive compression system comprising two communicating parties comprising the steps of transmitting, from the a first communicating party to the second communicating party, a device hierarchical node index; comparing the device hierarchical node index with a server hierarchical node index and then determining a shared hierarchical node index based on common entries in the two hierarchical node indexes.