In the database context, the hypertree decomposition method is used for query optimization,
whereby conjunctive queries having a low degree of cyclicity can be recognized and …

With the adoption of RDF as the data model for Linked Data and the Semantic Web, query
specification from end users has become more and more common in SPARQL endpoints. In …

Worst-case optimal join algorithms are attractive from a theoretical point of view, as they offer
asymptotically better runtime than binary joins on certain types of queries. In particular, they …

With the adoption of RDF as the data model for Linked Data and the Semantic Web, query
specification from end-users has become more and more common in SPARQL end-points …

This paper provides an in-depth and diversified analysis of the Wikidata query logs, recently
made publicly available. Although the usage of Wikidata queries has been the object of …

We present an indexing scheme that supports worst-case optimal (wco) joins over graphs
within compact space. Supporting all possible wco joins using conventional data structures …

We study the problem of optimizing one-time and continuous subgraph queries using the
new worst-case optimal join plans. Worst-case optimal plans evaluate queries by matching …

Worst-case optimal multiway join algorithms have recently gained a lot of attention in the
database literature. These algorithms not only offer strong theoretical guarantees of …

Regular path queries (RPQs) are a central component of graph databases. We investigate
decision-and enumeration problems concerning the evaluation of RPQs under several …

In this paper, we study local subgraph counting, which is to count the occurrences of a user-
given pattern graph p around every node v in a data graph G, when v matches to a given …