> > It would just be a standard "ALTER TABLE foo ALTER COLUMN bar TYPE > > newtype USING expression" operation. You would write a function that > > took a value of the old type and returned a value of the new type and > > use a cll to that function in the expression. Since these would be named > > types, unlike the case in mysql where they are anonymously defined > > inline, this would present no difficulties at all. > > But why force a re-write of the entire table just to change the name of > something? > > Or is ALTER COLUMN TYPE smart enough to not touch anything if the > mapping function is equality?
Nearly all ALTER TABLE commands are processed in the same way. In fact, in some cases they are combined (ADD column is broken down then re-combined later for a single rewrite). You could pretty easily add this type of logic to skip the rewrite stage if not needed. -- ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
