With the new Denodo Platform update (denodo-v80-update-20210209), Denodo offers the Direct Data Load feature to load the data directly into the data source when using the Cache, Remote Table and Summaries in Denodo .
Virtual DataPort server will detect automatically if it is possible to apply the optimization and will apply it by default.
If I want to impose restrictions on certain users to allow access to a virtual database, I would [create a role](https://community.denodo.com/docs/html/browse/latest/en/vdp/administration/databases_users_and_access_rights_in_virtual_dataport/administration_of_databases_users_roles_and_their_access_rights/creating_roles) and assign privileges for the role by selecting the specific database. Then, I would assign this role to the users such that the restrictions will be imposed accordingly.
You can take a look at the [User and Access Rights in Virtual DataPort](https://community.denodo.com/docs/html/browse/latest/en/vdp/administration/databases_users_and_access_rights_in_virtual_dataport/user_and_access_right_in_virtual_dataport/user_and_access_right_in_virtual_dataport#types-of-access-rights) section of Virtual DataPort Administration Guide for more information.
Hope this helps!