Hi there, We have upgraded some of our apps to Spring Boot 3, which also brings Hibernate 6. Since the upgrade we have noticed that the hibernate.jdbc.fetch_size property is not being respected. After some debugging I can see that the jdbcFetchSize field in SessionFactoryOptionsBuilder is being set…

From looking at the code, I can see that the JDBC fetch size is applied in org.hibernate.engine.jdbc.internal.StatementPreparerImpl#setStatementFetchSize. You can debug that to understand what is happening in your case.

I tried that but it never gets called. What I can see is that when running the query with Hibernate 6 it uses a StatementPreparationTemplate whereas on H5 it uses a QueryStatementPreparationTemplate.

Looks like a bug. Please create an issue in the issue tracker( https://hibernate.atlassian.net ) with a test case( hibernate-test-case-templates/JPAUnitTestCase.java at main · hibernate/hibernate-test-case-templates · GitHub ) that reproduces the issue.

@beikov @balazs Wanted to check if there is a bug created for this.

https://hibernate.atlassian.net/browse/HHH-16872 Following Bug has been created to track this.

jdbcFetchSize seems to be ignored

Hibernate ORM

balazs May 11, 2023, 9:19am 4

this is stack on H6

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Default_batch_fetch_size is unnecessarily respected when loading a one-to-many collection from a single entity object Hibernate ORM	2	1439	February 27, 2023
Retrieving a few records at one time from database with JPA Hibernate ORM	1	10085	March 27, 2018
Problem with @Generated and jdbc.batch_size Hibernate ORM	2	1839	February 9, 2023
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jdbcFetchSize seems to be ignored

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