Struzik V. Improving database refactoring technologies for information systems

The methods and approaches of refactoring at development of the software and databases are considered in the dissertation thesis. The classification of modern information systems is investigated and two approaches of building services are considered, namely: monolithic architecture template and microservice architecture template. Their advantages and disadvantages are described, as well as recommendations on the use of different options for interaction with databases in the development of microservice template architecture. This dissertation is based on the analysis of code refactoring and database refactoring. The main features of the need for refactoring, defects and problems of databases refactoring are given. The process of refactoring databases is described directly. The necessity of refactoring is substantiated, the recommendations on the choice of the appropriate refactoring operation and on the implementation of refactoring are given. Accordingly, the description and features of the refactoring categories and their operations are provided. The concept of semantic database versioning is formulated and recommendations are given for its application. The main focus and scientific novelty is the creation of a new category of refactoring, the creation of a specification of semantic versioning of database schema, the determining the place of refactoring in popular software lifecycles. Access refactorings category is accumulates operations that allow controlled implementation of changes in access control in the administration of the database management system, to create regulated processes of response to events related to security policy without information system downtime. Semantic versioning of the database schema makes it possible to understand whether the new version of the database is inversely compatible with the old version without further creation and study of corporate manifestos that would regulate the versioning of the database. An important advantage of semantic versioning of the database schema is the possibility of automated implementation of updates. It have been determined which place of refactoring is the most profitable in terms of time spent on system development and, as a consequence, financial costs. Based on this, the place of refactoring in popular software lifecycle models is defined. The place of refactoring determined in: cascade model, V-model, incremental model, RAD model, iterative model, spiral model. The approaches and methods proposed in the work have been tested and used during development and support in Ukrainian companies, which is confirmed by the relevant implementing acts.