* Starting in Oracle8i, latches can be acquired either as shared or exclusive. To exclusively acquire a latch or a mutex (available starting with Release 10.2), there can be no shared holders.

* While latches and mutexes ensure serialization, there is no ordering or queuing involved when a process is attempting to acquire the control structure. This is in distinct contrast to enqueues. As you'll learn in the next section, it is actually quite humorous how processes contend for a latch or mutex.

A few years ago, a separate chapter section on latching would not have made sense. But in Oracle 10g Release 2, mutexes were introduced to complement latches. Although latches and mutexes serve the same purpose, they are different enough to warrant their own section. But don't forget that latches are not an Oracle invention. Oracle has numerous patents and also acquires know-how by acquiring other companies. But like other database vendors, Oracle uses the term latch to describe a memory control structure.