Can queries containing deterministic user defined functions be cached in mysql query cache?
Based on some experimentation with MySQL 5.5.33, the answer is "no".  I have a function definition which is deterministic (it's a simple date calculation) and is marked as DETERMINISTIC.  If I use it in a query, the query is not cached.  If I replace the call by its definition in terms of the built-in date_sub() function, the query is cached.