Can you summarize the technique used? As far as "join table" goes, App Engine's datastore isn't relational. Filtered queries will work differently and were built with scalability characteristics in mind. Sometimes these characteristics will overlap with functionality that SQL provides and may even produce similar looking GQL, but at some level, it'll be different. Our goal is to make as much of the Google infrastructure as we can available for developers. The datastore is built on top of BigTable, which is itself not relational. Rather than think of your data in terms of SQL schema, it'd be advantageous to think of how you would store data in a key/value store - this is really the secret to success. If you have a chance, watch our Google I/O presentations from last year:
http://sites.google.com/site/io/ Here's one example of how certain problems are solved using App Engine's datastore: <http://sites.google.com/site/io/> http://sites.google.com/site/io/building-scalable-web-applications-with-google-app-engine <http://sites.google.com/site/io/building-scalable-web-applications-with-google-app-engine>Here's a good video describing how the datastore works underneath the hood: http://sites.google.com/site/io/under-the-covers-of-the-google-app-engine-datastore You'll want to watch these and read some of the articles we've published when you start needing to doing more complex queries: http://code.google.com/appengine/articles/ In the end, it's all about how you structure your data. Traditional RDBMS emphasizes normalization. We do not. App Engine emphasizes denormalization, favoring precalculated results for low latency responses to user requests. On Wed, Jan 27, 2010 at 6:24 PM, asianCoolz <[email protected]> wrote: > sure. the link is > http://groups.google.com/group/google-appengine-java/browse_thread/thread/b9e6a61357c4445d > > Ikai, can give any tips what roadmap JGAE plan to improve on > datastore? is that no way in the future to do "join table" ? and have > to use this technique? > > -- > 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 > [email protected]. > To unsubscribe from this group, send email to > [email protected]<google-appengine-java%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. > > -- Ikai Lan Developer Programs Engineer, Google App Engine http://googleappengine.blogspot.com | http://twitter.com/app_engine -- 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 [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
