I have a similar problem and none of the above proposals work. I'm trying to do an array_overlap(column_array, user_input_array). The user_input_array should be optional. So I can do something like select case when cardinality(column_array) = 0 or cardinality(user_input_array) > 0 then true else array_overlap(column_array, user_input_array) end as matched. However this won't work because the SQL UI won't allow empty input parameters.