Computation & communication in R^∗: A distributed database manager

R∗ is an experimental prototype distributed database management system. The computation needed to perform a sequence of multisite user transactions in R∗ is structured as a tree of processes communicating over virtual circuit communication links. Distributed computation can be supported by providing a server process per site which performs requests on behalf of remote users. Alternatively, a new process could be created to service each incoming request. Instead of using a shared server process or using the process per request approach, R∗ creates a process associated with the computation of the user on the first request to the remote site. This process is incorporated into the tree of processes serving a single user and is retained for the duration of the user computation. This approach allows R∗ to factor some of the request execution overhead into the process creation phase, and simplifies the retention of user and transaction context at the multiple sites of the distributed computation.