Re: alter table drop column status

Christopher Kings-Lynne wrote:
> 
> > No there was an unapplied hack which uses logical/physical
> > attribute numbers. I have synchronized it with cvs for a
> > year or so but stop it now. Though it had some flaws It
> > solved the following TODOs.
> >
> > * Add ALTER TABLE DROP COLUMN feature
> > * ALTER TABLE ADD COLUMN to inherited table put column in wrong place
> > * Prevent column dropping if column is used by foreign key
> 
> This seems fantastic - why can't this be committed?  Surely if it's
> committed then the flaws will fairly quickly be ironed out?  Even if it has
> flaws, then if we say 'this function is not yet stable' at least people can
> start testing it and reporting the problems?
> 
> > I gave up to apply the hack mainly because it may introduce
> > the maintenance headache.
> 
> Is it a maintenance headache just for you to keep it up to date, or how
> would it be a maintenance headache if it were committed?

Probably(oops I don't remember well now sorry) the main
reason why I didn't insist to apply the patch was that
it wasn't so clean as I had expected.
My trial implementation uses logical(for clients) and
physical (for backend internal) attribute numbers but
there were many places where I wasn't able to judge which
to use immediately. I'm pretty suspicious if a developer
could be careful about the choise when he is implementing
an irrevant feature. (Un)fortunately the numbers have
the same values mostly and he could hardly notice the
mistake even if he chose the wrong attribute numbers.
I'm not sure if I myself chose the right attribute numbers 
everywhere in my implementation.
In addtion (probably) there were some pretty essential
flaws. I intended to manage the backend internal
object references without the logical attribute
numbers but I found it difficult in some cases
(probably the handling of virtual(not existent 
in any real table) tuples).

Sorry it was more than 1 year ago when I implemented
it and I can't remember well what I'd thougth then.
Though I'd kept my local branch up to date for
about a year, it's about half a year since I touched
the stuff last. 

regards,
Hiroshi Inoue