Re: ALTER TABLE

On Fri, 2003-08-29 at 04:22, Hannu Krosing wrote:
> Rod Taylor kirjutas R, 29.08.2003 kell 03:31:
> > I've been fiddling away on ALTER TABLE and have a few questions about a
> > possible datatype change. Just alter portions.
> > 
> > I presume I'll need to do a table rewrite. What is the best way to
> > change a single datum?  heap_modify() takes a single relation type where
> > I will need to deal with different types.  Simply build a new tuple with
> > old datums (easy enough)? Do we care about OIDs being renumbered?
> 
> AFAIK alter table change column should do the equivalent of
> 
> alter table x add column temp_name newdatatype;
> update table x set temp_name=convert(name);
> alter table x drop colum name;
> alter table x rename column temp_name to name;

I presume we want the attnum needs to be preserved to preserve the
constraints that are pointing at the column.  Yes, constraints may need
a cast injects (view too), but if we're not going to do that there is
little advantage over doing the job by hand. as the above 4 step
process.