BARQ: A Vectorized SPARQL Query Execution Engine

Abstract

Stardog is a commercial Knowledge Graph platform built on top of an RDF graph database whose primary means of communication is a standardized graph query language called SPARQL. This paper describes our journey of developing a more performant query execution layer and plugging it into Stardog's query engine. The new executor, called BARQ, is based on the known principle of processing batches of tuples at a time in most critical query operators, particularly joins. In addition to presenting BARQ, the paper describes the challenges of integrating it into a mature, tightly integrated system based on the classical tuple-at-a-time Volcano model. It offers a gradual approach to overcoming the challenges that small- to medium-size engineering teams typically face. Finally, the paper presents experimental results showing that BARQ makes Stardog substantially faster on CPU-bound queries without sacrificing performance on disk-bound and OLTP-style queries.