Hi Willi, I've been working quite extensively with UC Berkeley's CollectionSpace Django Web Apps which require writing some pretty complicated queries ( https://webapps.cspace.berkeley.edu). Reviewing the impressive work done by John Lowe and his team can give you a pretty good sense of what's possible. You can find them here: https://github.com/cspace-deployment/Tools/tree/master/datasources . One of the best ways to make things easier is by reading the Nuxeo documentation on VCS Tables, if you haven't done so already: https://doc.nuxeo.com/nxdoc/vcs-tables/ If you have any specific questions, or need more help, feel free to reach out. Hope this helps. -Yousuf