An object identifier (OID) is an identifier used to name an object. Structurally, an OID consists of a node in a hierarchically-assigned namespace, formally defined using the International Telecommunication Union-Telecommunication's (ITU-T) Abstract Syntax Notation standard (ASN.1). Vertica database objects are always assigned an OID. The OID can be used directly in some statements, such as HAS_TABLE_PRIVILEGE.

Source: Wikipedia