Hibernate and Database Integration – Top 3 challenges and their solutions

Database – an essential part of the application

Every application requires a well-defined and organized way of managing their data.  It also needs a standard and simple way to perform CRUD (create, retrieve, update, delete) operations, which is usually taken care of by different kinds of databases. Today the database has become an essential part of the enterprise application development. Whether it is in the form of a Relational Database Management System (RDMS), NoSQL, or Graph, they all promote the management of the application across a variety of data structures.

This blog discusses the most apparent challenges to the database integration which were experienced so far.

Database Integration – the expected challenges

Data integration provides a wide range of useful knowledge that can introduce new creative services for your business. However, data integration cannot be overcome without challenges. The new concepts like data mining and analytics can be clarified by digging into data and uncover insights. For decades, though, modern databases have addressed tough questions. Perhaps you may want to know how many engineers in some areas are actually qualified.

The use of the database in an application has its own conventional issues from the Developer’s viewpoint and from the Architect, Database Administrator (DBA), and Project Management’s viewpoint. Let’s understand the Developer’s problems and the common approach found in today’s industry.

Not all the Developers are well-versed with different kinds of databases and their operations.

Many engineers find it convenient in their routine life to work with the programming languages such as Java, .NET, PHP, Objective-C, etc. and find it quite difficult to deal with databases specific programming terminology like:

  • Structured Query Language (SQL) – Data Definition Language (DDL), Data Query Language (DQL), Data Manipulation Language (DML), Data Control Language (DCL)
  • Procedural Language extensions to the Structured Query Language (PL / SQL)

For any database, there are variations in writing SQL or PL / SQL scripts that create more complexity for engineers when switching between different application databases and client environments. There are several modern database architectures used for diverse environments. However, none of them offers complete distributed support. Also, when we work with an object-oriented system, there is a mismatch between the object model and the relational database such as granularity, inheritance, identity, associations, and navigation.

Object Relational Mapping (ORM) is one solution to manage such mismatches. A variety of ORM frameworks are introduced to ease the engineer’s life which allows them to deal with the database using their known programming language terminology. One such framework is Hibernate which is widely used across the IT industry.

Database using Hibernate – the unexpected challenges

It is a lightweight and ORM open-source tool based on Java. It overcomes all the constraints of our Java Database Connectivity (JDBC) function and communicates with the databases internally using the Java API.

As such, Hibernate does not face difficulties irrespective of whether it is deployed in the development or QA or production environments while using one instance of the standalone application. However, have you ever thought about how Hibernate would respond to the complex application scenario that usually occurs in the production environment?

For example, let’s brainstorm on these two scenarios:

  • Different applications are connected to the same database to access the common set of tables.
  • Multiple instances of the same application are deployed in a cluster for High Availability.

Without time, let me explain what challenges we could face in the above scenarios and how we may solve them in the Hibernate environment.

Challenge 1

Let’s assume that two applications are concurrently trying to insert a new record in the same table. One application uses hibernate and the other uses direct database queries. At that moment, there are chances of the primary key constraint violation.

Causes:
  • The mechanism to retrieve the value for the primary key ID column may cause the issue. Whether the application follows default auto incremental data type or table sequence or takes max ID and increment on each insert.
  • The maximum ID batch is implemented in the non-hibernate application then that may cause issues in the current hibernate-based application as they all follow their own copy of max id value and will never sync up to other instances.
  • The batch update approach may also cause the issue.
Solution:

To prevent such issues one can consider the following aspects:

  • The record with the given primary key value is already present in the table, so ensure that your insert query takes the unique primary key which is not present in the table.
  • Avoid using the maximum ID approach. By default, Hibernate uses a single database sequence for all its generated entities where the sequence reaches max value and the subsequence transaction fails due to the unavailability of the next unique value from the sequence.
  • Use sequence allocation size (1) to force and fetch updated sequence number from the database, when multiple applications are accessing the same database table.
Challenge 2:

Data fetched from the different instances of the application are not identical.

Causes:
  • This issue is very specific to the environment setup and not related to application business logic. This is indeed an odd scenario to reproduce and resolve in a local standalone development instance of the application.
  • This problem is related to Hibernate cache settings for improving performance and high-availability. If you add more application node to scale-up horizontally then hibernate L2 cache can create a problem if each node cache is not in sync with other nodes.
Solution:
  • Implement replicating cache using JGroup, Terracotta, or Hazelcast and improve your native database query performance with the profiling and indexing.
  • Disable L2 cache on all the Hibernate applications to avoid stale data issues, in case the underlying table is used by multiple applications where some uses hibernate while others directly interacting with the database. This will eliminate performance advantages through cache, however, you can still continue to use hibernate in your application and leverage the other benefits.
Challenge 3:

DDL statements are not supported in Hibernate

Solution:

It is better to execute DDL script separately direct on the database and update respected entity class structure in code manually

Conclusion

Working with databases without dependencies is reasonably simple with optimum solutions. In addition, developers must learn and incorporate different techniques in these environments as the demand for technology performance has increased in the last decade. Hope that the solutions will make database integration work much easier.

We will continue to share more of these experiences with our fellow developers!

Author
Maulik Bamania | Lead Software Engineer

Maulik Bamania is a lead software engineer at GS Lab and has over 13 years of experience in enterprise application design and development. He is an avid technology reader and likes to learn about the latest technology trends to deliver quality solutions for customers. He has experience across all the facets of application management including, development, management, deployment, and application support.