[Mediawiki-l] Variables in Wikitext & Browser Caching

[Rick DeNatale]

On 6/12/05, Jamie Bliss <astronouth7303 at gmail.com> wrote:
> What exactly is the difference between a cache purge and a null edit
> (besides the entry in recentchanges)?
 
One difference that I know of is that a null edit will cause any
category links within a template on the page to be re-examined.

Changing a template to either add or remove a category link does not
recategorize any pages which transclude the template until the page
itself is re-saved.  I think that this is because categorizing a page
involves database updates, and it would be too expensive to do this
everytime a page with a template was rendered for viewing.  Purging
the cache just causes re-rendering of pages.