Feature classes in a geodatabase in Db2

A feature class is a collection of geographic features, all of the same geometric type (point, line, polygon, multipoint, annotation, dimension, or multipatch). For example, you could store points for all the train depots along a railroad line in one feature class. In another feature class, you could store lines that represent all the railroad tracks.

Feature classes in a geodatabase in IBM Db2

Feature classes stored in geodatabases in a Db2 database have an ST_Geometry column to store spatial data. ST_Geometry is an abstract noninstantiable superclass, the subclasses of which are instantiable.

When you create a feature class in Db2 using an ArcGIS client, a table with an ST_Geometry column is created in the owner's schema. Also, records are added to the LAYERS, TABLE_REGISTRY, sde_geometry_columns, COLUMN_REGISTRY, sde_spatial_references (if you defined a spatial reference), and GDB_ITEMS tables in the sde user's schema to track information about the feature class. The GDB_ITEMTYPES table in the sde user's schema defines the type of data it is, in this case, feature class.

All feature class tables store nonspatial attribute information, an Object ID, and a shape field. The Object ID and shape fields can have different names, but they are required to be in the feature class.

Tip:

Annotation and dimension feature classes have additional required fields. See Managing annotation feature class properties and Dimension feature properties for a list of these fields.

Once you load or add data to the feature class, ArcGIS creates several i tables and stored procedures in your database. These stored procedures and i tables generate feature IDs for feature classes. The i tables contain a number in their name. This number corresponds to the REGISTRATION_ID of the feature class in the TABLE_REGISTRY table. Editing these tables or stored procedures is not supported and highly discouraged.

View a diagram of a feature class in Db2.

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Dashed lines indicate implicit relationships between columns; solid lines indicate explicit relationships between columns.

The ST_GEOMETRY_COLUMNS and ST_SPATIAL_REFERENCE_SYSTEMS tables are actually views and are depicted in gray to differentiate.