Citation: Pina, E.; Sá, F.; Bernardino, J. NewSQL Databases Assessment: CockroachDB, MariaDB Xpand, and VoltDB. Future Internet 2023, 15, 10. https://doi.org/10.3390/fi15010010 Academic Editor: Wolf-Tilo Balke Received: 11 November 2022 Revised: 19 December 2022 Accepted: 20 December 2022 Published: 26 December 2022 Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). future internet Article NewSQL Databases Assessment: CockroachDB, MariaDB Xpand, and VoltDB Eduardo Pina 1 , Filipe Sá 1 and Jorge Bernardino 1,2, * 1 Polytechnic of Coimbra, Institute of Engineering of Coimbra—ISEC, Rua Pedro Nunes, 3030-199 Coimbra, Portugal 2 Centre for Informatics and Systems of the University of Coimbra (CISUC), Polo II, Pinhal de Marrocos, 3030-290 Coimbra, Portugal * Correspondence: jorge@isec.pt Abstract: Background: Relational databases have been a prevalent technology for decades, using SQL (Structured Query Language) to manage data. However, the emergence of new technologies, such as the web and the cloud, has brought the requirement to handle more complex data. NewSQL is the latest technology that incorporates the ability to scale and ensures the availability of NoSQL (Not Only SQL) without losing the ACID properties (Atomicity, Consistency, Isolation, Durability) associated with relational databases. Methods: We evaluated CockroachDB, MariaDB Xpand, and VoltDB with OSSpal methodology and experimentally using the Star Schema Benchmark (SSB). The scalability and performance capabilities of each database were assessed. Results: Applying the OSSpal methodology, the results showed that MariaDB Xpand outperformed CockroachDB and VoltDB. On the other hand, we concluded that with Star Schema Benchmark, CockroachDB had better scalability, while VoltDB had a faster query execution time. Conclusions: CockroachDB and VoltDB are the best performing databases in terms of scalability and performance. Keywords: SQL; NewSQL; OSSpal; SSB; CockroachDB; MariaDB Xpand; VoltDB 1. Introduction Today’s business world is accelerating, where advances in web technology and the creation of Internet-connected sensors and mobile devices have resulted in huge datasets that need to be processed and stored like never before. Relational Database Management Systems, also known as RDBMS, are one of the most successful technologies in computing, being the default choice for model adoption in business worldwide and its SQL standard language [1–3]. A DBMS consists of a collection of programs and services that allow the user to insert, update, delete, and query the stored data, making it easier to maintain and access the data [4]. With the huge volume and complex evolution of data, businesses have started to look for alternatives that allow them to work with high volume, velocity, and variety. SQL’s increased capacity allows the management of huge amounts of data but is not sufficient for the requirements of Big Data, which demands rapid response and high scalability. With such challenges, Not Only SQL (NoSQL) offers resources such as flexibility and horizontal scalability [5], but despite supporting the capability of highly available data volume technologies, NoSQL systems do not ensure ACID properties [6]. NewSQL emerged as a set of innovative SQL database engines with high perfor- mance and scalability. These engines seek to promote the same performance and scalability improvement of NoSQL systems and design solutions that have the advantages of the rela- tional model, and the benefit of using SQL language and fulfilling the ACID properties [7]. In 2011, Matthew Aslett first used the term NewSQL in a business analysis report [8], which discussed the advent of new database systems. NewSQL systems come in differ- ent types, targeting different workloads and practices, opening up new opportunities in business, where real-time decisions are critical. Among several use cases, we have Future Internet 2023, 15, 10. https://doi.org/10.3390/fi15010010 https://www.mdpi.com/journal/futureinternet