Re: Why is NULL not indexable?

I was thinking about what this actually meant and came to the conclusion
that having
SELECT * FROM foo WHERE bar IS NULL
would always result in a sequential scan.

Or does it mean anything else?

Daniel Åkerud

> > I can't work out what the 'strategy' bit refers to. All I can find in
the
> > source code is references to tables of magic numbers. I guess what I
really
> > want to know is, how hard would it be to fix?
>
> I believe the main problem is that IS NULL and IS NOT NULL are not
> operators (they don't have pg_operator entries), and all of the planning
> and indexscan execution machinery is designed around operators. Binary
> operators, at that.
>
> It's possible that this could be hacked around by creating dummy
> pg_operator entries for them, but my bet is that cleaning up the loose
> ends and no-longer-valid coding assumptions would be a nontrivial task.
>
> regards, tom lane
>
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