Rewriting user-defined functions (UDFs)
User-defined functions are custom functions that can be defined in databases and in certain analytical and streaming engines such as Spark and Azure Stream Analytics. An example of a UDF could be a custom function to check whether a given value is a valid email address.
The DP-203 syllabus just mentions the topic as Rewriting user-defined functions. In a literal sense, this is just dropping a UDF and recreating a new one, as we do for SQL or Spark tables. However, I believe the syllabus committee might have referred to rewriting normal repetitive scripts as UDFs to make them efficient from a development perspective. Note that UDFs can also decrease runtime performance if not designed correctly. Let's look at the ways to create UDFs in SQL, Spark, and Streaming.
Writing UDFs in Synapse SQL Pool
You can create a user-defined function in Synapse SQL using the CREATE FUNCTION command in Synapse SQL. Here is an example of using the...
