The Oracle OS user is usually a highly privileged user, and using the same user for operating system interactions for every PDB is not recommended. Also, using the same OS user for operating system interactions from different PDBs may compromise data belonging to a given PDB.

In contrast, using an OS user described by a credential whose name is specified as a value of the PDB_OS_CREDENTIAL parameter helps ensure that operating system interactions are performed as a less powerful user and provides the ability to protect data belonging to one PDB from being accessed by users connected to another PDB. A credential is an object that is created using the CREATE_CREDENTIAL procedure for the DBMS_CREDENTIAL package.

The operating system interactions that are done as the OS user name specified in the credential include:

• External jobs that do not already have an operating system credential specified

• External table pre-processors

• PL/SQL library executions

This parameter can be specified for all the PDBs in a CDB but the CDB-wide value can be overridden for a specific PDB and can be modified only by a common administrative user with the EXECUTE privilege for the DBMS_CREDENTIAL PL/SQL package and the ALTER SYSTEM system privilege.

If a value is not set for this parameter for a given PDB, the Oracle OS User will continue to be used when interacting with the operating system from that PDB.