Why do you need the structure? Mendix handles the database all under the hood. And to note that HSQL is only used for your local database. In the Mendix cloud it is postgres. If you are looking for a way to export your data there are multiple options. You could create grids for all the entities you used in your model and have CSV export buttons there. Or create OData endpoints for all your entities you want to export. OData endpoints can also handle REST calls so there are then multiple ways for the other end to retrieve that data.

Regards,

Ronald