Issue with @GeneratedValue and SequenceStyleGenerator on SQL Server 2019/2022 with Hibernate 6.4.4

ADEAUTOMOBILE

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30-09-2024

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Hibernate 6.4.4 and SQL Server 2019/2022: Solving the @GeneratedValue and SequenceStyleGenerator Issue

Problem: You're using Hibernate 6.4.4 with SQL Server 2019/2022 and encountering difficulties when trying to utilize @GeneratedValue with a SequenceStyleGenerator. Specifically, you might see errors related to sequence generation, like "Sequence [sequenceName] not found."

Scenario:

Let's say you have a simple entity with an auto-incrementing ID:

@Entity
public class MyEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "mySequenceGenerator")
    private Long id;

    // other fields ...
}

And your persistence.xml configures a sequence generator:

<persistence>
    <persistence-unit name="myPU">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.SQLServerDialect"/>
            <property name="hibernate.sequence_style_generator.initial_value" value="1"/>
            <property name="hibernate.sequence_style_generator.increment_size" value="1"/>
        </properties>
    </persistence-unit>
</persistence>

This setup aims to use a database sequence named mySequenceGenerator for generating IDs. However, upon running the application, you might face the issue of Hibernate not finding the sequence, resulting in an exception.

Explanation:

The issue arises from a compatibility mismatch between Hibernate 6.4.4 and SQL Server 2019/2022. Prior to Hibernate 6, the SequenceStyleGenerator would automatically create sequences in the database if they were missing. However, this behavior changed in Hibernate 6, requiring explicit sequence creation.

Resolution:

1. Manual Sequence Creation:

   • You need to manually create the sequence in your SQL Server database. Use a SQL script like this:

   CREATE SEQUENCE [schemaName].[mySequenceGenerator]
   AS INT
   START WITH 1
   INCREMENT BY 1;
   

   • Make sure to replace [schemaName] with the appropriate schema name for your entity.
   • Ensure the sequence name matches the one specified in your @GeneratedValue annotation and persistence.xml.

2. Enable Sequence Creation (Hibernate 6.5+):

   • If you're able to upgrade to Hibernate 6.5 or later, you can enable sequence creation through configuration. Add the following property to your persistence.xml:

   <property name="hibernate.hbm2ddl.auto" value="create-drop"/> 
   

   • This will instruct Hibernate to create missing sequences (along with other schema elements) during startup. However, be cautious with this setting, as it can potentially modify your database schema if your entities change.

3. Use Identity Column (Alternative):

   • If you want to avoid manual sequence creation, consider using SQL Server's identity columns for auto-incrementing IDs. Remove the @GeneratedValue annotation and instead add the @Column(name = "id", columnDefinition = "INT IDENTITY(1,1)") annotation to your entity's ID field. This will rely on SQL Server's built-in identity column functionality for generating IDs.

Additional Tips:

• Naming Conventions: Ensure the sequence name in your SQL script matches the one specified in your entity and persistence.xml exactly, including case sensitivity.
• Schema Ownership: If your sequence resides in a different schema than your entities, make sure the Hibernate user has the necessary permissions to access and manipulate that schema.
• Logging: Enable Hibernate logging to debug potential issues related to sequence generation. This can provide valuable clues about the underlying problem.

Resources:

• Hibernate 6 Documentation: https://docs.jboss.org/hibernate/orm/6.4/userguide/html_single/
• SQL Server Documentation: https://docs.microsoft.com/en-us/sql/t-sql/statements/create-sequence-transact-sql?view=sql-server-ver16

Conclusion:

By understanding the compatibility changes introduced in Hibernate 6 and adopting the appropriate solution, you can effectively utilize @GeneratedValue and SequenceStyleGenerator with SQL Server 2019/2022. Remember to choose the approach that best suits your project's requirements and development workflow.