Hi @guangyi ,

I've just tested and following approach will work. Register similar Python UDF function in UC.

CREATE OR REPLACE FUNCTION catalog.schema.GetLength(strlen STRING)
RETURNS STRING
LANGUAGE PYTHON
AS $$
  return len(strlen)
$$

 Then you can refer to that function in materialized view:

CREATE MATERIALIZED VIEW length_verification
AS
select COUNT(department) as count
from dev.default.employee
where department is not null and dev.default.GetLength(department) > 1;