We consider the propagation of authorizations in distributed database
systems. We present an optimistic replica control algorithm that ensur
es that the authorization table at any given site evolves consistently
with respect to other sites. The motivation for using optimistic repl
ica control to maintain authorizations is that site and communication
failures do not needlessly delay authorization changes. In addition, t
he semantics of the authorization operations we employ can be exploite
d to resolve transient inconsistencies without the expense of an undo-
redo mechanism. Instead, we give efficient, direct algorithms whereby
a site scans its log of authorization requests and updates its authori
zation table correspondingly. From the system perspective, any inconsi
stencies in the authorization table replicas maintained at different s
ites are transient and are eliminated by further communication. We sho
w how a site can prune its authorization log by the use of a matrix th
at records how current remaining sites in the system are.