Hibernate ORM Pros and Cons

Hibernate solves a plethora of problems which a Java Developers may face during the course of developing their application. They may have to face difficulties such as repeating the same lines of code while composing their applications for obtaining the required data from the database. They may also have a hard time mapping objects to their database tables or find it tedious to implement OOPS (Object Oriented Programming Structure) with the JDBC code. It may also happen that they may find migration from one database to another very time consuming and there are many problems which pave the way while creating associations between tables using JDBC. All these problems are sifted, analysed and solved using an ORM tool like Hibernate.

About Hibernate
Just like the first question asked in the set of Hibernate interview questions, Hibernate has a long set of features that attract many companies. It constitutes an open source library created for Java so that objects can be mapped to an RDBMS (Relational Database Management System). It is also used to apply and use OOPS concepts in a relational database.

The Pros of Hibernate

• Hibernate promptly uses its own language known as HQL (Hibernate Query Language) to connect to the database. Queries are executed using this language and then the results are mapped to Java.
• Impedance mismatch: The problem of object-relational impedance mismatch occurs when a relational database is connected to an application coded in the style of OOPS. These impedance mismatches arise from differences in data types, transactions, data manipulation, structure, and integrity.
• Object Mapping- Hibernate automatically connects Java classes to database tables with the help of XML and annotations. The developer just needs to write the code which maps the object model’s data representation to a relational model and its corresponding schema.
• HQL- Just like SQL, queries in Hibernate are written using Hibernate Query Language (HQL). The difference between the two is that HQL supports polymorphic queries. It understands OOPS concepts such as polymorphism, inheritance, and association.
• Database Independence- The queries used in HQL don’t change if databases are changed, such as MySQL or Oracle. This makes communication with a database as well as migration to a new database simpler.

The Cons of Hibernate

• Hibernate is not a good option for applications that are simple and require only one database. Applications which only include placing the data in the database tables with no further SQL queries will also find Hibernate cumbersome. Hibernate is also a disadvantage for applications that don’t need to map their objects to 2 different tables. Hibernate attaches a level of complexity as it increases the number of layers in the system and using Hibernate in the above scenarios causes a large amount of overhead for these applications which can affect their speed and functionality.
• Complex data will take several iterations for the object-to-table mapping which reduces the performance and increments the time taken for conversion.
• It doesn’t allow the insertion of multiple objects in the database using a single query like JDBC. A separate query has to be written for each object.