Last checked and updated on April 16, 2026What Is New in HSQLDB 2.3
HSQLDB 2.3 delivers a substantial update focused on SQL standard compliance, performance, and reliability. This version introduces new features, enhances existing ones, and resolves numerous issues from previous releases.
| Category | Key Changes |
|---|---|
| New Features | SQL:2016 window function enhancements, new built-in functions, improved support for data types including JSON. |
| Improvements | Faster query execution, reduced memory footprint, optimized transaction handling. |
| Bug Fixes | Over 50 fixes addressing crashes, data corruption issues, and incorrect query results. |
| Deprecations | Legacy syntax and features marked for removal in future versions. |
What are the major SQL standard compliance updates?
Version 2.3 pushes HSQLDB closer to full SQL:2016 core conformance. The most significant additions are in window function capabilities, bringing it on par with other major databases.
You now get better handling of RANGE and ROWS clauses, along with more complete support for framing options within window functions. This matters because it allows for more complex analytical queries directly in the database without post-processing.
How has performance been improved?
The engine's optimizer and query execution plans have been refined for greater efficiency. These changes result in faster response times for complex joins and aggregations.
In practice, you'll notice the biggest gains with queries that use subselects and correlated expressions. Memory management is also smarter, reducing overhead for applications with many concurrent connections.
What critical bugs were fixed?
This release squashes several pesky bugs that could cause data file corruption or incorrect query results under specific conditions. The fixes cover areas from transaction rollbacks to index handling.
One notable fix resolves an issue where certain MERGE statements could fail silently. Another prevents potential crashes when using GROUP BY with specific aggregate functions.
FAQ
Are there any backward-incompatible changes I should worry about?
Most changes are additive, but some deprecated legacy behaviors from early HSQLDB versions may finally be removed. Check the release notes for a specific list if you're upgrading from a very old version.
Does 2.3 improve the in-memory mode for testing?
Yes, the mem: protocol has seen optimizations that make it even faster for unit tests. The startup time for creating temporary databases is noticeably quicker.
Is JSON support now production-ready?
The JSON functions are more robust and performant in this release. For simple storage and retrieval tasks, it's solid, but for heavy JSON processing, evaluate it against your specific workload.
What's the single biggest reason to upgrade?
The collective weight of over 50 bug fixes. It significantly enhances the stability and reliability of your database compared to 2.2.
Have the JDBC driver connections been improved?
Connection pooling and cleanup have been made more efficient, which helps prevent resource leaks in long-running applications.