An ML Engine user-defined function (UDF) is a programming construct that accepts parameters, uses the accepted parameters, and returns a result. These functions use the syntax and APIs similar to ML Engine functions. ML Engine does not support the development of these functions. However, if you have a UDF developed on Aster Database, you can install and execute it in ML Engine. The execution of a UDF is the same as ML Engine function execution. A UDF invocation gets its data from Advanced SQL Engine, executes in ML Engine, and returns the results to Advanced SQL Engine.