###### Abstract  
The role of databases is to allow for the persistence of data, no matter if they are of the SQL or NoSQL type. In SQL databases, data are structured in a set of tables in the relational database model, grouped in rows and columns. CRUD operations (create, read, update, and delete) are used to manage the information contained in relational databases. Several dialects of the SQL language exist, as well as frameworks for mapping Java classes (models) to a relational database. The question is what we should choose for our Java application, and why? A comparison of the most frequently used relational database management systems, mixed with the most frequently used frameworks should give us some guidance about when to use what. The evaluation is conducted based on the time taken for each CRUD operation to run, from thousands to hundreds of thousands of entries, using the possible combinations in the relational database system and the framework. Aiming to assess and improve the performance, the experiments included the possibility of warming-up the Java Virtual Machine before the execution of queries. Also, the research investigated the time spent using different methods of code to determine the critical regions (bottlenecks). Thus, the conclusions provide a comprehensive overview of the performances of Java applications accessing databases depending on the suite decisions considering the database type, the framework in use, and the type of operation, with clear comparisons between the alternatives, the key findings of the advantages and drawbacks of each of them, and supporting architects and developers in their technological decisions and improving the speed of their programs. J 2024202024202  
accessing the database; using another method, we may have to consider portability, the amount of code to be written, and the development speed. A developer should be aware of his application's needs to be able to pick the right combination, generally being able to choose, as a framework, between JPA, Hibernate [6; 7], and Spring Data JPA [8]. This paper expands upon previously published work and experiments, summarizes them, and focuses on improving the execution speed and detecting bottlenecks. This will help developers to choose the option that best fits their Java [2; 3] application. Picking a framework randomly might not be the best solution to start an application. The proposed research approach is to run an average-complexity application with different frameworks and dialects on a Windows operating system and to test the necessary time to handle different numbers (up to 500 thousand entries) of each CRUD operation. The amount of code and its simplicity will also be taken into consideration when the comparison is made. The research approach includes the following steps:  
1. The design of the database that will serve as the experimental support. 2. The design and implementation of the Java program that will interact with the database. This includes the Java classes and tests that use different frameworks to work with the database (JPA, Hibernate, Spring Data JPA). 3. Running a Java test will be completed on a single thread, using combinations of all previously mentioned frameworks and different relational database servers (MySQL using the InnoDB engine, Oracle, PostgreSQL, and Microsoft SQL Server), and we will present the experimental results in tables and graphics. 4. Improving performances using JMH with one warm-up iteration and one execution iteration, running Java tests using combinations of all the mentioned frameworks and database servers, collecting the experimental results in tables and graphics, and comparing them with previous results. 5. Identifying the bottlenecks and the code sections that require the most time to be executed. MySQL [9] is an open-source RDBMS with a large user base. It is widely used for developing web applications, as it has a low cost and simple installation process. Its capabilities include replication, full-text search, and support for different storage engines.