[imp] Upgrading DB schemas

[R Phillips]

When upgrading minor versions, say from the Webmail groupware edition
from 4.0.3 to 4.0.5 there are some DB scheme changes.

Is it possible to see whether those changes are significant, in that an
upgraded test install of horde/imp could be run against the same
database as a current live version?

It's probably best to copy the existing database and run the test
version against the copy, but if the changes are limited to additional
database indexes/new columns then it would be possible without affecting
the live version.  Other than actually taking a copy and comparing after
upgrade, is there an easy way of comparing the old/new schema?