[wp-hackers] Why WP mantain old post slug?

[Pixline › Paolo Tresso]

> A user asked me why even after chamging a post slufg the old one vas
> still searchable and the old url still active redirectong to new post.

It's a feature, not a bug.

This is intended for both SEO and URL canonicalization. If you have an  
old post well indexed (or just linked by someone) you'll probably want  
to keep it's SEO blessing even if changing its slug.

This way, if you change that slug and someone tries the old address,  
you'll be redirect (with the proper HTTP header) to the new url,  
without any loss or risk.

This was (is?) also useful for many WP users who couldn't afford fancy  
permalinks (because of their windows hosting, or after a huge  
migration, for example), this trigger lets them to change permalink  
structure without losing search engine indexing, and without breaking  
any external link.

As far as I know there is at least one plugin who gives an interface  
to this thing, but I can't find it in my bookmarks, sorry.

Paolo/Pixline