3.4.4. ORM Layer
Object-Relational Mapping is a technology for linking relational database tables to programming language objects. CUBA uses the ORM implementation based on the EclipseLink framework.
ORM provides some obvious benefits:
Enables working with a relational DBMS by means of Java objects manipulation.
Simplifies programming by eliminating routine writing of SQL queries.
Simplifies programming by letting you load and save entire object graphs with one command.
Ensures easy porting of the application to different DBMS.
Enables use of a concise object query language – JPQL.
At the same time, there are some drawbacks too. First of all, a developer working with ORM directly should have a good understanding of how it works. Also, ORM makes direct optimization of SQL and usage of the DBMS specifics difficult.
If you have any performance issues with the database access, the first thing to check is what SQL statements are actually executed. Use