Modifications to table variables
UPDATE, INSERT and DELETE on table variables cause a completely serial plan. SELECT statements, on the other hand, don’t neccessarily.
Completely serial. Even when they’re used in computed columns in one of the tables. Even when you’re not referencing that actual column.
Not all computed columns generate serial plans – only those with scalar functions.
Read on for a number of other places. It turns out that this set is pretty stable from 2012 through to 2017.