HDT (Header-Dictionary-Triples) is a compressed representation of RDF data that supports retrieval features without prior decompression. Yet, RDF datasets often contain additional graph information, such as the origin, version or validity time of a triple. Traditional HDT is not capable of handling this additional parameter(s).

This work introduces HDTQ (HDT Quads), an extension of HDT that is able to represent quadruples (or quads) while still being highly compact and queryable. Two HDTQ-based approaches are introduced: Annotated Triples and Annotated Graphs, and their performance is compared to the leading open-source RDF stores on the market.

Results show that HDTQ achieves the best compression rates and is a competitive alternative to well-established systems.

J.D. Fernández, M.A. Martínez-Prieto, A. Polleres, J. Reindorf, HDTQ: Managing RDF Datasets in Compressed Space, ESWC. The Semantic Web (2018) 191-208