An analytical study of large SPARQL query logs

Abstract

With the adoption of RDF as the data model for Linked Data and the Semantic Web, query specification from endusers has become more and more common in SPARQL endpoints. In this paper, we conduct an in-depth analytical study of the queries formulated by end-users and harvested from large and up-to-date query logs from a wide variety of RDF data sources. As opposed to previous studies, ours is the first assessment on a voluminous query corpus, spanning over several years and covering many representative SPARQL endpoints. Apart from the syntactical structure of the queries, that exhibits already interesting results on this generalized corpus, we drill deeper in the structural characteristics related to the graph-and hypergraph representation of queries. We outline the most common shapes of queries when visually displayed as pseudographs, and characterize their (hyper-)tree width. Moreover, we analyze the evolution of queries over time, by introducing the novel concept of a streak, i.e., a sequence of queries that appear as subsequent modifications of a seed query. Our study offers several fresh insights on the already rich query features of real SPARQL queries formulated by real users, and brings us to draw a number of conclusions and pinpoint future directions for SPARQL query evaluation, query optimization, tuning, and benchmarking.

Approximate Querying on Property Graphs

“…We restrict RPQs to handle atomic paths -bi-directional, optional, singlelabeled (l e , l e ?, and l − e ) and transitive single-labeled (l * e ) -and composite paths -conjunctive and disjunctive composition of atomic paths (l e · l e and π + π). While not as general as SPARQL, our fragment already captures more than 60% of the property paths found in practice in SPARQL query logs [8]. Moreover, it captures property path queries, as found in the large Wikidata corpus studied in [9].…”

“…However, arbitrarily complex queries [2,3,7], entailing rather intricate, possibly recursive, graph patterns prove difficult to evaluate, even on small-sized graph datasets [4,5]. On the other hand, the usage of these queries has radically increased in real-world query logs, as shown by recent empirical studies on SPARQL queries from large-scale Wikidata and DBPedia corpuses [8,17]. As a tangible example of this growth, the percentage of SPARQL property paths has increased from 15% to 40%, from 2017 to beginning 2018 [17], for user-specified Wikidata queries.…”

A comparative survey of recent natural language interfaces for databases

“…There are also no unions (Q5) and no questions with multiple subqueries (Q10). Bonifati et al (2017) investigated a large corpus of query logs from different SPARQL endpoints. The query log files are from seven different data sources from various domains.…”

How many and what types of SPARQL queries can be answered through zero-knowledge link traversal?

“…To our knowledge, our work is the first that i) analyses real query logs from known endpoints for finding popular patterns of queries that can be answered or cannot be answered through zeroknowledge link traversal, and ii) provides open source methods to detect answerable queries and transform them to SPARQL-LD queries that are evaluated without accessing endpoints or indexes. While recent works have conducted extensive analytical studies on the syntactical and structural characteristics of real SPARQL queries [1,2,25], no previous work has analysed queries in terms of their answerability through link traversal.…”