Semih Salihoglu

In an era of increasingly interconnected information, graph-structured data has become pervasive across numerous domains, from social media platforms and telecommunication networks to biological systems and knowledge graphs. However, traditional database management systems often struggle when confronted with the unique challenges posed by graph-structured data, in large part due to the explosion of intermediate results, the complexity of join-heavy queries, and the use of regular path queries. This monograph provides a comprehensive overview of modern query processing techniques designed to address these challenges. Four key components that have emerged as pivotal in optimizing queries on graph-structured databases are focused on, namely: (1) Predefined joins, which leverage precomputed data structures to accelerate joins; (2) Worst-case optimal join algorithms, that avoid redundant computations for queries with cycles; (3) Factorized representations, which compress intermediate and final query results; and (4) Advanced techniques for processing recursive queries, essential for traversing graph structures. For each component, theoretical underpinnings are covered and design considerations are explored, and implementation challenges associated with integrating these techniques into existing database management systems are discussed. This monograph aims to serve as a comprehensive resource for both researchers pushing the boundaries of query processing and practitioners seeking to implement state-of-the-art techniques, in addition to offering insights into future research directions in this rapidly evolving field.

The last decade has seen a huge and growing interest in processing large data sets on large distributed clusters. This trend began with the MapReduce framework, and has been widely adopted by several other systems, including PigLatin, Hive, Scope, Dremmel, Spark and Myria to name a few. While the applications of such systems are diverse (for example, machine learning, data analytics), most involve relatively standard data processing tasks like identifying relevant data, cleaning, filtering, joining, grouping, transforming, extracting features, and evaluating results. This has generated great interest in the study of algorithms for data processing on large distributed clusters. Algorithmic Aspects of Parallel Data Processing discusses recent algorithmic developments for distributed data processing. It uses a theoretical model of parallel processing called the Massively Parallel Computation (MPC) model, which is a simplification of the BSP model where the only cost is given by the amount of communication and the number of communication rounds. The survey studies several algorithms for multi-join queries, sorting, and matrix multiplication. It discusses their relationships and common techniques applied across the different data processing tasks.