Each persistent class has an extent, which consists of all saved instances of that class. See “Introduction to Persistent Objects” in Using Caché Objects.
Maintains extent definitions and globals registered for use by those extents. Extent definitions most commonly originate from compiling a persistent class but can also be defined outside of any class. This class provides a public interface for deleting extent definitions and registering the extents of all managed extent classes or a single class.
In addition to the public interface implemented here, the %ExtentMgr tables are visible to SQL and can be queried directly. There are two examples implemented in this class: GlobalUses() and GlobalsUsed(). Both are public class methods that return a single result set and both are projected as stored procedures and can be invoked by dynamic SQL, embedded SQL or through an xDBC client. These methods are more important as examples of how the %ExtentMgr tables can be queried.
Availability: All namespaces.