1. A computer-implemented method for maintaining group membership records, at least a portion of the method being performed by a computing device comprising at least one processor, the method comprising: maintaining a record of group memberships for a membership hierarchy, the record of group memberships identifying: a first degree relationship between a first object and a second object in the membership hierarchy, a first degree relationship between the second object and a third object in the membership hierarchy, and a first degree relationship between the third object and a fourth object in the membership hierarchy; receiving a membership update indicating that, as of a first point in time, the first degree relationship between the first object and the second object has changed; deducing, based on the membership update, a change in a second degree relationship between the first object and the third object and a change in a third degree relationship between the first object and the fourth object as of the first point in time, wherein the changes in the second and third degree relationships are deduced in a single pass such that the change in the third degree relationship is deduced without first deducing the change in the second degree relationship.