Having looked at the null comparisons, let’s see how they behave in
ordering and indexing. For ordering purposes, in a bow to practicality, NULLs are considered to be equal to each other in terms
of grouping, because, hey, if they were not, ordering them wouldn’t be very useful.
WITH ordertest AS ( SELECT NULL UNION ALL SELECT 2 UNION ALL SELECT 1 UNION ALL SELECT NULL ) SELECT * FROM ordertest ORDER BY 1; ?column? ---------- 1 2 (null) (null)