title: Mix of MySQL and Mongodb in an application
body: <p>I'm writing a web application using PHP/Symfony2/Doctrine2 and just finishing up the design of the Database. We have to import these objects (for ex. Projects, Vendors) into our database that come from different customers with variety of fields. Some customers have 2 fields in the project object and some have 20. So I was thinking about implementing them in MongoDB since it seems like a good use for it. </p>
  
  <p>Symfony2 supports both ORM and ODM so that shouldn't be a problem, Now my question is how to ensure the integrity of the data in both databases. Because <strong>Objects in my MySQL db need to somehow be linked to the objects in the MongoDB</strong> for integrity issues.</p>
  
  <p>Are there any better solutions out there? Any help/thoughts would be appreciated</p>