If you import overrides, consider the following rules and guidelines:
Import process converts session overrides into corresponding parameter types.
When you import SQL-based overrides into the Model repository, the import process converts the overrides into a SQL parameter type. For example, when you import the PowerCenter mapping into the Model repository, the Pre SQL and Post SQL changes to an SQL parameter type. Also, a user-defined join and source filter converts to an SQL parameter type.
The remaining session override properties convert to String or to the corresponding parameter types. For example, Reject file converts to a String parameter type.
In PowerCenter, if you use a mapping parameter of the String type in session override properties, such as user defined joins, SQL query, or Post SQL, the import process brings in the referenced parameter as a String type. You should manually change the type of the mapping parameter assigned to the properties to SQL type after import.