Re: cascading column drop to index predicates

On Mon, 2003-12-22 at 10:55, Tom Lane wrote:
> Andreas Pflug <pgadmin@pse-consulting.de> writes:
> > In that sample mentioned the index might be used mostly with a,b 
> > columns. Dropping the index silently might damage the application 
> > because it relies on an (a,b) index to be present. IMHO only Indexes 
> > that span that single column should be dropped without CASCADE.
> 
> That argument makes no sense to me at all.  If you drop the *column*
> a or b, and do not thereby break your application, how is the
> disappearance of the index on it going to break anything?  The index
> is meaningless without something to index.

I think Andreas is trying to argue that if you drop column b from index
(a, b) that the index should be converted into index(a) -- assuming of
course there isn't already an index(a).