Evolving NoSQL Databases Without Downtime

NoSQL databases like Redis, Cassandra, and MongoDB are increasingly popular because they are flexible, lightweight, and easy to work with. Applications that use these databases will evolve over time, sometimes necessitating (or preferring) a change to the format or organization of the data. The problem we address in this paper is: How can we support the evolution of high-availability applications and their NoSQL data online, without excessive delays or interruptions, even in the presence of backward-incompatible data format changes? We present KVolve, an extension to the popular Redis NoSQL database, as a solution to this problem. KVolve permits a developer to submit an upgrade specification that defines how to transform existing data to the newest version. This transformation is applied lazily as applications interact with the database, thus avoiding long pause times. We demonstrate that KVolve is expressive enough to support substantial practical updates, including format changes to RedisFS, a Redis-backed file system, while imposing essentially no overhead in general use and minimal pause times during updates.Comment: Update to writing/structur

Test model for database architectures: an assessment for job search engine systems

Information systems are increasingly complex structures due to the diversity of processes involved and the big data generated, hence data management is essential. NoSQL databases adopt new approaches to data management differing from relational structures. In this study, three databases were designed, a relational database using PostgreSQL and two NoSQL databases made in MongoDB applied to operation of a job offer system, with the aim of comparing its operation and efficiency. A method was proposed for the metric-guided evaluation of database models using functionality and efficiency criteria according to Systems and Software Standard Quality Requirements and Evaluation (SQuaRE). Testing cases were created considering the International Software Testing Qualifications Board (ISTQB) best practices. Relational data model was selected as a pattern, for this reason, to populate NoSQL databases a reference framework was applied for data migration from one environment to another, thus the tests were performed under the same hardware, software and data conditions. This study determined that the SQL schema provides greater functionality, ensuring transaction support and data integrity. On the other hand, the NoSQL schemas are more efficient in response to big data processing, although they have a certain level of data duplication, transaction support fails and some join operations are not support

Der Lehrstuhl Datenbank- und Informationssysteme der Universität Rostock

Im Jahr 2014 feierte der Lehrstuhl Datenbank- und Informationssysteme (LS DBIS) an der Universität Rostock sein zwanzigjähriges Bestehen. Zur Jubiläumsveranstaltung mit ehemaligen und aktuellen Studenten, Mitarbeitern, Kollegen und Kooperationspartnern wurde diverses Material aus 20 Jahren aufbereitet. In diesem Beitrag soll daraus ein Rückblick auf 20 Jahre Forschung und Lehre im Bereich Datenbank- und Informationssysteme sowie ein Ein- und Ausblick auf aktuelle Forschungsarbeiten gegeben werden

Evolution Management in NoSQL Document Databases

NoSQL databases are widely used for many applications as a technology for data storage, and their usage and popularity rises. The first aim of the thesis is to research the existing approaches and technologies for schema evolution in NoSQL databases. Next, we introduce an approach for schema evolution in multi-model databases with a unified interface for the most common data models. The proposed approach is easy to use and covers the common migration scenarios. We have also implemented a prototype, optimized its read/write operations, and demonstrated its properties on real-world data. 1NoSQL databáze jsou široce používány v mnoha aplikacích jako technolo- gie pro ukládání dat. Jejich použití a popularita stále roste. Prvním cílem této práce je shromáždit a analyzovat existující řešení a technologie pro evoluci schéma v NoSQL databázích. Dále představujeme obecné řešení pro evoluci schéma v multi-model databázích s jednotným rozhraním pro nejběžnější da- tové modely. Navržené řešení je jednoduše použitelné a pokrývá scénáře běžných migrací. Součástí práce je i implementace optimalizovaného prototypu navrho- vaného přístupu a demonstrace jeho vlastností na datech z reálného světa. 1Katedra softwarového inženýrstvíDepartment of Software EngineeringFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult