I would say that this exactly what a relational database is for. My first approach would be to have a managed bean (session scope) to read/access user's data in MySQL (JDBC). If you want, you can build an internal cache inside the bean.
For the presented use case, I would not bother with the JDBC datasources in ExtLib. Perhaps even the @Jdbc functions would suffice.
Also, you did not say how you are doing the analysis? If you store the information in Domino, you'll probably have to write an export tool.