I believe Avenue is referring here to the sui generis database right
the section sui generis, not the one "Copyright"). This only exists in
Database rights are relevant for new data imported into Wikidata by
Europeans from those European databases that have no license which
addresses database rights (such as CC0, ODbL, etc.).
As far as my analysis goes, they do not affect Wikipedia, however. The
database right protects the database as a whole, not individual
records (although records can be protected as part of the database).
The database right for the database as a whole is automatically given
to the employer or the single person creating the entire database.
Both cases do not apply in the case of Wikipedia. WMF is not European,
does not employ editors, and most likely none of those editors which
reside in the EU can claim to have created an entire and complete
I am not a lawyer - please correct should my analysis be wrong.
(PS: The fact that the unported CC 3.0 licenses are silent on database
rights, whereas several ported (de, fr, nl) explicitly waive database
rights is a known issue and under discussion in the CC version 4.0