I know Jena SDB has been end of life since Dec 2020. Nevertheless, I wonder what SDB stands for. Is is Statement Data Base or Semantic Data Base? Even referring to Jena's homepage, there was no answer to that.
It doesn't stand for anything. It is "SDB".
The previous system was "RDB".
The successor is "TDB".
Vaguely and not formally:
RDF DataBase
SPARQL DataBase
Tuple DataBase