In ArcGIS 9.x if a Feature Class is registered with a Class Extension the CLSID of the extension is recorded in a table in the sde schema called sde.GDB_OBJECTCLASSES (EXTCLSID field).
However in ArcGIS 10 there is no such table, and I can't find anything comparable in an SDE 10 database. I assume this information must now be stored in the data server's registry, but I am not sure where to start.
I am trying to debug issues apparently caused by an upgraded (ArcGIS v10) Class Extension updating data in a Feature Class originally registered with a v9.3 Class Extension and held in a v9.3 SDE database (both versions of the extension share the same GUID), so any insight on this would be much appreciated.
Best Answer
In the geodatabase items table GDB_Items there will be an extry for the FeatureClass. The definition field of this entry contains the DEFeatureClassInfo definition and this has an EXTCLSID entry. For more on the new GDB schema introduced at 10.0, start with this blog post.