Re: cascading column drop to index predicates

Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au> writes:
> The thing is, if you drop a column that is used in a normal index, yes
> the index is now useless - drop it.
> However, since you can have (and I have) indexes like this:
> CREATE INDEX asdf ON table (a, b, c) WHERE d IS NOT NULL;
> If I drop column d, there is no way I want that index to just disappear!

Uh, why not? I don't quite see the argument why d stands in a different
relationship to this index than a,b,c do. The index is equally
meaningless without any of them.

> Can we change it to requiring a CASCADE?

It'd likely be a simple code change, but first let's have the argument
why it's a good idea.

regards, tom lane