ASA Database Administration Guide
Database Options
Introduction to database options
DBA authority is required to set an option for the PUBLIC user ID.
Changing the value of an option for the PUBLIC user ID sets the value of the option for all users who have not SET their own value. An option value cannot be set for an individual user ID unless there is already a PUBLIC user ID setting for that option.
Some options which can only be set for the PUBLIC user take effect immediately for existing connections, even though the changed setting will not be visible to users via the connection_property() function. An example of this is the global_database_id option. For this reason, PUBLIC-only options should not be changed while other users are connected to the database.