24. A method employed in a versioned relational database system of performing a change propagation operation that propagates a change to or from a version of a table that is accessible via a workspace in the versioned relational database system, the change propagation operation being performed on a version in a given workspace that has more than one parent workspace, a processor and a storage device accessible to the processor being used to implement the versioned relational database system, and the method comprising the steps performed in the processor of: determining which workspaces in the versioned relational database system belong to a multi-parent graph that has a leaf workspace, two or more intermediate workspaces, and a root workspace, the given workspace being the leaf workspace; using the multi-parent graph to determine workspaces in addition to the given workspace whose versions are affected by the change propagation operation; and performing the change propagation operation on the version in the given workspace and on the additional workspaces whose versions are affected by the change propagation operation.
24. A method employed in a versioned relational database system of performing a change propagation operation that propagates a change to or from a version of a table that is accessible via a workspace in the versioned relational database system, the change propagation operation being performed on a version in a given workspace that has more than one parent workspace, a processor and a storage device accessible to the processor being used to implement the versioned relational database system, and the method comprising the steps performed in the processor of: determining which workspaces in the versioned relational database system belong to a multi-parent graph that has a leaf workspace, two or more intermediate workspaces, and a root workspace, the given workspace being the leaf workspace; using the multi-parent graph to determine workspaces in addition to the given workspace whose versions are affected by the change propagation operation; and performing the change propagation operation on the version in the given workspace and on the additional workspaces whose versions are affected by the change propagation operation. 36. The method set forth in claim 24 further comprising the step of: in propagating the changes, using the multi-parent graph to determine versions which must be checked for a constraint violation.