Feature datasets in a geodatabase in Db2
Feature datasets are objects that allow you to group together related feature classes so they can participate in specific functionality. Use a feature dataset to group feature classes that have the following characteristics:
- They are stored in the same coordinate system.
- They participate in a topology.
- They participate in a relationship class.
- They are part of a geometric network, network dataset, utility network, schematic dataset, parcel fabric, or terrain dataset.
- They have associated feature-linked annotation.
Feature datasets in a geodatabase in IBM Db2
In the database, feature datasets are virtual collections of feature classes. They are grouped together by a common ID, which is maintained in the GDB_ITEMS geodatabase system table.
For the Water feature dataset example, the feature class, Tanks, is identified as part of the Water feature dataset through the GDB_ITEMRELATIONSHIPS table. The UUID of the feature dataset is the ORIGINID, and the UUID of the feature class is the DESTID.
The following shows the Tanks feature class business table and the system tables that track the Water feature dataset in Db2:
Because feature datasets are virtual collections of objects, feature classes in feature datasets are just like stand-alone feature classes in that they have their own records in the tables associated with feature classes such as LAYERS, TABLE_REGISTRY, sde_geometry_columns, and COLUMN_REGISTRY. Since feature classes associated with feature datasets are database objects in their own right, they cannot have the same name as other tables or stand-alone feature classes in the same schema in the database.
Tip:See Feature classes in a geodatabase in Db2 for a diagram of feature class relationships in the geodatabase.
Topologies, networks, parcel fabrics, schematic datasets, and terrain datasets are additional database objects that can be part of a feature dataset. These objects use additional system tables, which are described in separate topics.