SaGe: A Preemptive SPARQL Server for OnlineKnowledge Graphs

In order to provide stable and responsive SPARQL endpoints to the community, public SPARQL endpoints enforce fair use policies. Unfortunately, long-running SPARQL queries cannot be executed under fair use policy restrictions, returning only partial results. To address this issue, we proposed SaGe, a SPARQL server based on the Web preemption principle. Instead of stopping queries after a quota of time, SaGe suspends the current query and returns it to the user. The user is then free to continue executing the query from where it was stopped, by simply sending the suspended query back to the server. In this paper, we describe the current state of SaGe, including the latest advances on the expressiveness of the server and its ability to support updates