Incremental Knowledge Graph Construction from Heterogeneous Data Sources

Sharing datasets that change (through creates, updates, deletes) poses challenges to data consumers, including reconciling historical versioning and managing frequent changes. This is evident for Knowledge Graphs (KGs), materialized from such datasets, where synchronization happens through frequent regeneration. However, this is time-consuming, loses history, and wastes computing resources through redundant processing. We present a KG generation approach that efficiently handles evolving data sources with different change signaling strategies. We investigate change signaling strategies of real-world datasets, propose corresponding change detection algorithms, and introduce a declarative approach based on the RDF Mapping Language (RML) and Function Ontology to materialize changes for evolving KGs. Detected changes can be automatically published as a Linked Data Event Stream (LDES), using the Activity Streams 2.0 vocabulary to describe changes and communicate them over the Web. We implement our approach in the RMLMapper as Incremental RML and evaluate it both functionally, and quantitatively using a modified version of the GTFS Madrid Benchmark and several real-world data sources. Our approach reduces storage and computing requirements for generating and storing multiple KG versions (up to 315.83x less storage, 4.59x less CPU time, and 1.51x less memory) and reduces KG construction time up to 4.41x. Performance gains are more pronounced for larger datasets, while our approach's overhead partially offsets benefits for smaller ones. Overall, our approach lowers the cost of publishing and maintaining KGs and, via LDES, supports timely, Web-native dissemination of changes. We plan to optimize our change detection algorithms and use windowing to support streaming data.