What is an ObjectID?

An ObjectID is a unique, not null integer field used to uniquely identify rows in tables in a geodatabase. ObjectIDs are limited to 32-bit values, which store a maximum value of 2,147,483,647.

Tables that are created through ArcGIS, or created outside ArcGIS then registered with the geodatabase, automatically have an ObjectID field added to them. The values in this field are maintained by ArcGIS. The ObjectID is used by ArcGIS to do such things as scroll, display selection sets, and perform identify operations on features.


Since most ArcGIS for Desktop functionality requires that the ObjectID be unique, you must be sure that ObjectID values are not duplicated when working directly with the database outside of ArcGIS. For example, when creating views with a one-to-many relationship, there is the possibility that ObjectIDs will be duplicated. This causes inconsistent behavior in ArcGIS for Desktop functionality.

When is an ObjectID added to a table?

There are several ways an ObjectID is added to a table: