Version 5.4.23.Final of Hibernate ORM is available now: allow me to highlight some fixes and enhancements.

Memory improvements

Thanks to Barthel Steckemetz for having analyzed the retained heap consumption of a SessionFactory in HHH-14271.

This allowed to identify some low hanging fruits to make it possible to lose some of the weight an Hibernate ORM instance brings to your applications.

Motivated by these findings we made additional improvements, including in the cost of metadata being allocated during the introspection on entities during early bootstrap.

We ended up improving also Hibernate Commons Annotations, which you will find has been upgraded to version 5.1.2.Final.

I’d love to get more data about the impact it has on your applications. In some syntethic benchmarks using code generation, this has shown to reduce memory consumption up to 50%, but we have to consider that our tests are definitely biased, as we meant to exacerbate problems with the model so to easily spot them using heap analysis tools. One the other hand Barthel reported improvements in the same ballpark for his real application, and only had a preliminary version of these patches.

If you’re inclined to share more data and hint at possible solutions, we’d be happy to help improve even further.

Quarkus and Hibernate Reactive

This version and all its improvements have already been integrated in both our prototype of Hibernate Reactive and within Quarkus, which will feature them in the next release.

This update is particularly exciting in the context of Quarkus: since it already runs Hibernate ORM with very minimal overhead, having Hibernate itself become lighter produces a very efficient combination.

Oracle cursors

A bug in our integration code made us mistakenly disable the use of RefCursors on all Oracle JDBC drivers, including the versions which were reporting to support this.

Essentially the mistake in our code was reporting that the driver didn’t support this feature, even on recent versions which actually support it.

This fix should now allow to use RefCursor automatically on all drivers which report supporting the feature.

N.B. older versions of the Oracle JDBC driver didn’t support this at all, so if you want to benefit from this it’s also a good idea to check if you need upgrading drivers.

Detailed changelog

You can find the full list of changes in this version here.

Getting Hibernate ORM 5.4.23.Final

All details are available and up to date on the dedicated page on

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