What is an objectID?

An objectID is a unique, not null integer column used to uniquely identify rows in tables in a geodatabase. ObjectIDs are limited to 32-bit values, which store a maximum value of 2,147,483,648.

Tables that are created through ArcGIS, or created outside ArcGIS then registered with ArcSDE and the geodatabase, must contain an objectID column that is maintained by the geodatabase. The objectID is used by ArcGIS to do such things as scroll and display selection sets and perform identify operations on features.


Since most ArcGIS Desktop functionality requires the objectID to be unique, caution should be used when working directly with the database so that objectIDs are not duplicated. 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 Desktop functionality.

There are three ways a qualifying objectID is added to a table: