Heikki Linnakangas napsal(a):
> It the new attribute is added to the end, the old tuples will be
> compatible as is. If there's no null bitmap (or it's shorter than
> expectd), attributes missing from a tuple are implicitly NULL. That's
> how we support ALTER TABLE ADD COLUMN without rewriting all the data.
>
Yeah, but better is to put int column before chunk data. It save space
(alignment). I prefer to put attno as a third column.
Zdenek