Erik Darling whips up a performance test covering scalar UDF changes in SQL Server 2019:
This is a slightly different take on yesterday’s post, which is also a common problem I see in queries today.
Someone wrote a function to figure out if a user is trusted, or has the right permissions, and sticks it in a predicate — it could be a join or where clause.
If you do need to use scalar UDFs, SQL Server 2019 is a big step forward.