app engine urlfetch cache clearing

Question

Is there a command to do a one time clear of all urlfetch cached data?

Have found this

http://www.mail-archive.com/[e-mail]/msg09869.html

which seems to clear on a url by url basis

Answer 1

No. Caches - whether as part of urlfetch or elsewhere - cache pages publicly. Multiple users may try to fetch the same page, and get the same cached result. Thus, clearing the cache would clear it for everyone.

HTTP provides headers for bypassing caching, as the link you referenced indicates. These are what you should use if you need to avoid retrieving cached results.