Calculating MD5 is very fast in GAE: from time import time from hashlib import md5
s = '1'*100 t = time() for i in xrange(1000000): md5(s).digest() print time() - t result: 1.4655559063 I remember the key name is limited to 500 bytes long, so it may exceed if you combine several keys into one. ---------- keakon My blog(Chinese): www.keakon.net Blog source code: https://bitbucket.org/keakon/doodle/ On Wed, Dec 15, 2010 at 2:43 PM, johnP <j...@thinkwave.com> wrote: > I need to create a large amount of records which relate three other > entities. Just for example, take 100 people; 100 days; and 100 > restaurants. To create a record for an intersection of a person/day/ > restaurant, it's possible to create keyname of person.key()+day.key() > +restaurant.key(). And to retrieve records, it's easy to generate a > list of keys and use a db.get(). > > In the internet somewhere, I read a comment by Nick Johnson saying > that long keynames are inefficient, and that it can be a good idea to > use a MD5 or SHA1 hash function to shorten the key name. My question > is, how expensive are the MD5 and SHA1 functions? > > For example, if I need to generate 100 keys for each view (e.g. to > retrieve people who visited 1 restaurant in 1 day, I can generate 100 > keys and db.get() that list) - is it cheaper to use the MD5 hash to > keep key_names shorter? Or is the cost of generating the hashes more > than any savings from shortening the keys? > > > > > -- > 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-appeng...@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine+unsubscr...@googlegroups.com<google-appengine%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine?hl=en. > > -- 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-appeng...@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
