On Apr 6, 5:23 am, Jeff Schnitzer <[email protected]> wrote: > The thread-local transaction model that JPA/JDO inherited from EJB > assumes the flexibility of RDBMS transactions that let you touch any > piece of data you want. That just doesn't work on appengine. > > Jeff
Don't forget that JDO did not inherit the EJB transaction model, per se. JPA does, due to its lineage. There are things in JDO that depend to a certain degree on the ACID properties of transactions, which may break down against GAE/J's BigTable. However, DataNucleus has been happily building plugins for other nonrelational stores. I can't speak for them, but they indicate that there are, thus far, no issues where the semantics of JDO conflict with these other stores (Cassandra, Hadoop, etc). There is an issue entered with JDO, https://issues.apache.org/jira/browse/JDO-651, that is there to address any specification modifications that need to be made to support NoSQL datastores. It appears, though, that BigTable's entity groups may be a different enough beast from the other NoSQL databases that it can't be treated like them. Hard to say. Good or bad, definitely give your feedback on your JDO experiences to DataNucleus and the GAE/J team, particularly Max Ross. The issue tracking systems are at the following locations: https://issues.apache.org/jira/browse/JDO http://code.google.com/p/googleappengine/issues/list Squeaky wheels and all, you know. -matthew -- 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.
