I am not sure what you meant by fan out and fan in but I agree with you that in relational world, data are more consistent as they are stored and enforced by constraints etc. but demoralized form does not requires joins, which makes them more scalable as less overhead.
If one high level entity exits in multiple groups, yes it is waste of (google's) storage space and more update are needed but isn't map reduce had proven that it is still less intensive than table joins? Sent from my HTC on the Now Network from Sprint! ----- Reply message ----- From: "Ikai Lan (Google)" <ika...@google.com> Date: Fri, Aug 5, 2011 3:13 pm Subject: [appengine-java] Joins! To: <google-appengine-java@googlegroups.com> -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
