> And what happens when we implement NULLS FIRST/LAST correctly? This is
> really a poor choice of representation.
If it's just appending of indexscan's it's not a problem...
>
> One thing I find questionable about this is the assumption that indexes
> can support "foo IS NULL" and "foo IS NOT NULL" searches equally
> conveniently. This is demonstrably false for, say, hash. (Hash could
> store null keys by assigning them a fixed hashcode, say 0. Then it
> would be able to handle IS NULL searches, but not IS NOT NULL, because
> it can't do full-index scans.)
Is there a guarantee that hash value of some not-null keys doesn't equal to
special hash code?
>
> the patch to do IS NULL only. But if we are going areto support both,
> we probably have to have two pg_am flags not one.
GiST isn't effective with single NOT NULL condition ... So, using two flags may
be useful.
--
Teodor Sigaev E-mail: teodor@sigaev.ru
WWW: http://www.sigaev.ru/
