The Cluster Edition also uses retention locks, which are cluster-wide locks granted to instances in the cluster with ownership shared among all processes on the instances. Ownership of a retention lock is retained until another instance claims a conflicting lock mode, or the resource associated with the lock is claimed by another instance. The use of retention locks reduces the need to acquire and release locks, and thus reduces intra-instance messaging.
The Cluster Edition uses several different retention locks.
All locks are retention locks.
