multiple-databases

I am developing a Django application which will use multiple database backends. I would like to put an sqlite database on the machine running the django application, and sync to a remote mysql database. The tricky part is that this machine running the application will not always have an internet connection, so the mysql database is not always availalble. There will be multiple machines running the application, each with it's own local sqlite DB, but all using the same remote mysql DB. I haven't written the code yet, but here is what I have in mind. Every time I run an insert or update I would

In my Qt application, I have a base class as follow. I am using QObject because I want to use Signal-Slot mechanism in all derived classes. class IRzPlugin : public QObject { public: virtual void registerMenu(QWidget*); virtual void execute(); } Then I have another class as follow. I need to extend from QWidget because I need to implement event handling methods in all derived classes.(mouseMoveEvent(),keyPressEvent()..etc); class IRzLayeringPlugin : public IRzPlugin , public QWidget{ } But compiler gives these the errors: C:\svn\osaka3d\tags\iter08\prototype\osaka3d\rinzo\plugin\moc

I am trying to use 2 persistence units within the same transaction in a Java EE application deployed on Glassfish. The 2 persistence units are defined in persistence.xml, as follows: <persistence-unit name="BeachWater"> <jta-data-source>jdbc/BeachWater</jta-data-source> ... <persistence-unit name="LIMS"> <jta-data-source>jdbc/BeachWaterLIMS</jta-data-source> ... These persistence units correspond to JDBC resources and connection pools which I had defined in Glassfish as follows (include one here as both are identical apart from names & database connection info): JDBC Resource: JNDI Name: jdbc

We have a Rails app hosted on Heroku and i need to set up some analytics pages for our marketing guy. This seems to be the typical use case for a Heroku follow database The 2 databases will share the same model classes, i want only some action to query the replicated database. What is the preferred way to handle this situation in my app ? ActiveRecord::Base documentation talks about class specific connection : You can also set a class-specific connection. For example, if Course is an ActiveRecord::Base, but resides in a different database, you can just say Course.establish_connection and

In the following piece of code (Spring 3): @Transactional("txManager") public class DaoHolder { @Transactional(value="txManager", readOnly=false, propagation=Propagation.REQUIRES_NEW, rollbackFor={Exception.class}) private void runTransactionalMethod() throws Exception { dao1.insertRow(); dao2.insertRow(); //throw new Exception(); } //... } dao1 uses a session factory attached to datasource1 dao2 uses a session factory attached to datasource2 txManager is a HibernateTransactionManager using the same session factory as dao1 The code above works correctly in a transactional manner - in