Hey Greg and Joshua, Entity groups really aren't that hard, once you play with them and do some testing, I promise ;).
First thing to note is that entity groups have effectively nothing to do with the entity's kind. It has to do with the entity's key; or, more precisely, its path. Entity's in the same group have the same path prefix and so are stored "together," and they can be operated on transactionally. The relationship is parent-child in the same sense that a file has a parent directory. You could think of them almost as a sub-database. There are limits, however, to the frequency you can write entities in the same entity group (I think 2 or 3 per second is stated in the docs). Also, because the entity group is stored in the key it can not be changed once the entity has been saved. Hopefully that is not more confusing. :) Robert On Wed, Jul 13, 2011 at 20:41, Greg <g.fawc...@gmail.com> wrote: > On Jul 13, 1:05 am, Joshua Smith <joshuaesm...@charter.net> wrote: >> Frankly, I've never completely groked what an entity group maps to in my >> (30+ years of) programming experience. It's certainly not a parent/child >> relationship in the usual sense. > > If you figure it out, let me know! I have a app that needs to update > two distinct entity types at the same time. Because they are distinct, > I can't do both in a transaction. Even if it was only one entity type, > I don't want to lock all of them when writing to one, which I believe > is a consequence of making them a group. > > A good article called "entity groups for dummies" seems warranted! > > -- > 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 > google-appengine+unsubscr...@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-appengine@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.
