Journal of Universal Computer Science
CQL, Continuous Query Language is suitable for data stream queries. Sometimes it is better if the queries operate on relational databases and data streams simultaneously. The execution of a CQL query takes a long time (several hours, days or even more). It is not clear what kind of semantics is suitable for the user when the database is updated during the execution of a CQL query. In this paper the authors give a short description of CQL, a characterization of update-problems, and they offer possible suggestions for the semantic extension of CQL.