Re: full featured alter table?

On Thu, 12 Jun 2003, Sven Koehler wrote:

> > Pretty much when someone who cares about it enough comes along with
> > a sufficient plan (and preferrably code) to implement it without breaking
> > things would be my guess (especially given that AFAICS it's not part of
> > either SQL92 or SQL99). Note that a sufficient plan would possibly
> > involve a lot of things not directly involved with changing the type
> > such as being able to deal with cached query plans for functions and
> > such.
>
> In other word, nobody cares about that at the moment, and so this will
> not be implemented.

Actually, it's more that it's a big job (bigger than actually just
changing the column) and it has some side issues about things like storage
(can we use 2x space to do it, do we need to do something else, what
happens if it fails part way due to something like a failure to convert
data), stored plans (do plpgsql functions and foreign keys continue
functioning after it, what about set returning functions that return that
type), and probably other things that I can't think of. With limited
resources, you have to make choices about what you work on. I'm sure Tom
(for example) could have done it, but he possibly wouldn't have been able
to do some or all of the error code stuff, protocol changes, expression
indexes, various optimizer enhancements, bug fixes, etc.

> something i hate most about opensource movement are these comments like
> "submit a patch". your staments are not that rough, but i'd need more
> time to get into the code than to implement the feature.
> so if this feature was never foreseen, than it might get a heavy task,
> and it might be even havier in a few years to implement that.

It's actually probably going to move towards being easier over time
hopefully, since some of the side issues are things that are probably
going to be addressed anyway.