If multiple pages alias from the same location, such as if both HardSecurity and SoftSecurity alias from HardAndSoftSecurity, then provide an auto-generated disambiguation (see WikiPedia:Wikipedia:disambiguation) page - "do you want to read about SoftSecurity or HardSecurity?".
If there is in fact a page at AbsentLeaders, then render any aliases from there as SeeAlso links. AbsentLeaders is rendered as a link to a non-existent page. By clicking on it, a user can start adding content to AbsentLeaders. Which is one way of undoing the redirect/alias. The other way is to edit AbsentLeader and remove the PageAlias statement from the top.
You can implement PermanentAnchors by allowing a PageAlias statement to be placed at arbitrary location in each page. Equivalently, if you implement PermanentAnchors in the right way, you get PageAliases for free.
the above text is PrimarilyPublicDomain
I would be very surprised if the PageDatabase actually turned out more efficient. Rather than scouring every page every time you write a WikiWord just to see if there's an alias, chances are redirects would be implicitly created in the PageDatabase. -- ChrisPurcell (Kritter)