Yeah, it's tough either way. I'm fine with just discarding urls that exceed 500 characters (that was my first solution), although I agree that the key space is probably large enough that hash collisions would be highly unlikely.
On Oct 2, 12:31 pm, Bill <[EMAIL PROTECTED]> wrote: > > Then I think your only solution is to do it yourself (the > > "tinyurl" service), assuring uniqueness. Basically, you "only" need to > > mix datastore simple Gets with hashtable behaviour (taking care and > > assuming that two different urls, despite rare, can result in the same > > hash key). You need to query by hash key and then, among the results, > > look for the matching url. Most of the time (depending on the url->key > > algorithm) you should get few results, so overhead won't be a problem. > > The above assumes that there'll be collisions when you map from urls > to the key name. I might naively assume that with a large enough key > space (500 characters), you should be able to find a hashing function > that'll pretty much guarantee unique keys to be generated. > > My first question, though, would be if the urls that are greater than > 500 characters can be truncated or simply not permitted. When I've > seen really long urls on previous apps, they've been attacks by bots > or urls with all kinds of state information. You could impose a > restriction on submitted URLs and I think a very small % of URLs would > trip it. Anyone know stats of valid URLs by length? > > Since I also plan on implementing a Digg-like function on one of my > websites, I'm interested in good hashing functions that let you > produce a reasonably sized hash (less than 500 char) efficiently. > Seems like the SHA hashes are overkill. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~----------~----~----~----~------~----~------~--~---
