I have an integer column that is not needed for some rows in the table
(whether it is necessary is a factor of other row attributes, and it
isn't worth putting in a separate table).
What are the performance tradeoffs (storage space, query speed) of using
NULL versus a sentinel integer value?
Not that it matters, but in the event where the column values matter,
the numberic value is a foreign key. Advice on that welcome too.
Thanks!