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.
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