# Issue with DB2iDialect and Sequence Support in Hibernate 6

**URL:** <https://discourse.hibernate.org/t/issue-with-db2idialect-and-sequence-support-in-hibernate-6/11715>\
**Category:** Hibernate ORM\
**Created:** [August 7, 2025, 8:40pm UTC](https://discourse.hibernate.org/t/issue-with-db2idialect-and-sequence-support-in-hibernate-6/11715 "2025-08-07T20:40:50Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![gijsm](https://avatars.discourse-cdn.com/v4/letter/g/f14d63/32.png) [@gijsm](https://discourse.hibernate.org/u/gijsm)\
**Post date:** [August 7, 2025, 8:40pm UTC](https://discourse.hibernate.org/t/issue-with-db2idialect-and-sequence-support-in-hibernate-6/11715/1 "2025-08-07T20:40:50Z")

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Hello,

I have a question regarding the `DB2iDialect` in Hibernate. It appears to support sequences and uses the following SQL to fetch sequence data:

```auto
SELECT DISTINCT sequence_name  
FROM qsys2.syssequences  
WHERE current_schema = '*LIBL'    
AND sequence_schema IN (SELECT schema_name FROM qsys2.library_list_info)     
OR sequence_schema = current_schema 

```

However, the dialect uses `SequenceInformationExtractorDB2DatabaseImpl`, which extends `SequenceInformationExtractorLegacyImpl`. In the `extractMetadata` method, it triggers the above query and attempts to read several columns (e.g., `sequence_name`, `start`, `increment`, etc.). Since the query only returns `sequence_name`, this results in a runtime exception.

Am I missing something, or is it the case that `DB2iDialect` doesn’t support sequences?

**Context:**

- I’m using a DB2 (IBM i V7R4M0) database.

- I have a JPA entity that I cannot modify.

- The entity uses `@GeneratedValue(strategy = GenerationType.AUTO)`.

- With Hibernate 5.6, the dialect defaults to SEQUENCE, but I was able to override this by setting:

Now I’m upgrading to Spring Boot 3.6.4 and Hibernate 6. This property has been removed, and I haven’t found an alternative. Since I cannot change the generation type on the entity, I’m trying to switch to using sequences — but the current dialect setup fails due to the issue above.

**Questions:**

- Is `DB2iDialect` supposed to support sequences properly in Hibernate 6?

- Is there a workaround or recommended approach for this situation, given the limitations?

Thanks in advance!

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**Author:** ![beikov](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/beikov/32/258_2.png) [@beikov](https://discourse.hibernate.org/u/beikov)\
**Post date:** [August 8, 2025, 10:18am UTC](https://discourse.hibernate.org/t/issue-with-db2idialect-and-sequence-support-in-hibernate-6/11715/2 "2025-08-08T10:18:07Z")

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As far as I understand, DB2 for i is supposed to support sequences as of version 7.3, but we heard of other people having trouble before, see [HHH-19453](https://hibernate.atlassian.net/browse/HHH-19453). Unfortunately, we don’t have a way to test IBM DB2 for i yet and so we don’t really know if we are missing something.

Clearly, this query misses to produce select items with the following aliases

- seqname
- seqschema
- start
- minvalue
- maxvalue

I created [HHH-19453 Fix sequence information extraction on DB2 for i by beikov · Pull Request #10713 · hibernate/hibernate-orm · GitHub](https://github.com/hibernate/hibernate-orm/pull/10713) to fix this and will backport the fix. I’d be very grateful if you could help us with testing of the dialect in the meantime. Can you run the Hibernate ORM testsuite on an isolated database for testing?

Just checkout the branch for my PR, add the following entry to `local-build-plugins/src/main/groovy/local.databases.gradle` and run `./gradlew check -Pdb=db2i`:

```auto
            db2i : [
                    'db.dialect' : 'org.hibernate.dialect.DB2iDialect',
                    'jdbc.driver': 'com.ibm.db2.jcc.DB2Driver',
                    'jdbc.user' : 'orm_test',
                    'jdbc.pass' : 'orm_test',
                    'jdbc.url' : 'jdbc:db2://' + dbHost + ':50000/orm_test',
                    'jdbc.datasource' : 'com.ibm.db2.jcc.DB2Driver',
// 'jdbc.datasource' : 'com.ibm.db2.jcc.DB2SimpleDataSource',
                    'connection.init_sql' : ''
            ],

```

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<div class="post-metadata">

**Author:** ![gijsm](https://avatars.discourse-cdn.com/v4/letter/g/f14d63/32.png) [@gijsm](https://discourse.hibernate.org/u/gijsm)\
**Post date:** [August 9, 2025, 11:38pm UTC](https://discourse.hibernate.org/t/issue-with-db2idialect-and-sequence-support-in-hibernate-6/11715/3 "2025-08-09T23:38:50Z")

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> [@beikov](#):
>
> HHH-19453 Fix sequence information extraction on DB2 for i by beikov · Pull Request #10713 · hibernate/hibernate-orm · GitHub

Seems like the branch is already merged and deleted but i will test it on the main branch.