Complex types are reference types. You MUST check if they are null first before using them.
Maximum size of a complex value
There is no specific limit inherent to Complex Types
However, rowsets must still fit within the limits defined by U-SQL (currently no row can be bigger than 4MB)
Complex Types can be stored in and read from U-SQL Tables without any additional effort.
To read/write Complex Types with files, you must use your own Custom Outputter & Extractor.