Question: You created a temporary datafile in the Primary database, but it did not get created in the Standby database. How to create tempfiles at standby node?

New tempfiles are not added automatically in the Physical Standby database because no redo is generated. Tempfiles in the Standby are only used when your Standby is opened in read-only mode.

When you add tempfiles in the Primary database, new tempfiles are not added automatically on the Physical Standby database because no redo is generated.

The tempfile auto-creation only kicks in when the Standby controlfile already contains the tempfile name.

You need to open the Physical Standby database in read-only mode. This allows you to add a temporary file.

SQL> alter database open read only.
SQL> alter tablespace temp add tempfile '[name]' size ..