Fast Construction of Compressed Web Graphs.

Several compressed graph representations were proposed in the last 15 years. Today, all these representations are highly relevant in practice since they enable to keep large-scale web and social graphs in the main memory of a single machine and consequently facilitate fast random access to nodes and edges. While much effort was spent on finding space-efficient and fast representations, one issue was only partially addressed: developing resourceefficient construction algorithms. In this paper, we engineer the construction of regular and hybrid k(2)-trees. We show that algorithms based on the Z-order sorting reduce the memory footprint significantly and at the same time are faster than previous approaches. We also engineer a parallel version, which fully utilizes all CPUs and caches. We show the practicality of the latter version by constructing partitioned hybrid k-trees for Web graphs in the scale of a billion nodes and up to 100 billion edges.