Last checked and updated on 05 Jun 2026
What Is New in MariaDB 5.5
MariaDB 5.5 is a long-term support (LTS) release based on MySQL 5.5 with many additional improvements from MariaDB 5.3. It was the first stable release in the 5.5 series in April 2012 and received maintenance until May 2020.
This version focused on better performance through an enhanced thread pool, improved storage engine options, replication flexibility, and practical new tools for monitoring and compatibility.
Major Features and Improvements
| Area | Feature | Description |
|---|---|---|
| Performance | Thread Pool | Significantly more efficient thread pool, offering performance comparable to MySQL Enterprise Edition's closed-source thread pool. |
| Storage Engine | SphinxSE | Updated to version 2.0.4 for better full-text search integration. |
| Storage Engine | Extended Keys | Support for extended keys in both XtraDB (default) and InnoDB. |
| Plugins | INSTALL SONAME |
New statement to install plugins by shared library name. |
| Optimizer | LIMIT ROWS EXAMINED |
New optimization to limit the number of rows examined during query execution. |
| Replication | Dynamic Filter Variables | replicate_do_*, replicate_ignore_*, and replicate_wild_* variables are now dynamic and can be changed without restarting the server. |
| Monitoring | SQL_ERROR_LOG plugin | New plugin to log SQL-level errors for easier troubleshooting. |
| Compatibility | old_mode variable |
New system variable to enable compatibility mode with older MariaDB or MySQL behavior. |
InnoDB and XtraDB Enhancements
MariaDB 5.5 uses **XtraDB** as the default storage engine but allows easy switching to the standard InnoDB.
- Extended key support for both XtraDB and InnoDB.
- InnoDB can be loaded as a plugin using options such as
ignore-builtin-innodbandplugin-load=innodb=ha_innodb.so. - Performance Schema table updates are no longer written to the binary log, reducing replication overhead and preventing potential crashes on replicas.
Other Notable Changes
Additional improvements include:
- New status variables for monitoring feature usage and server activity.
mysql_real_connect()now preserves options after a failed connection attempt (from 5.5.21).- New tables added to
INFORMATION_SCHEMAfor better visibility. - PBXT storage engine removed from binary distributions (still available in source code) due to lack of active maintenance.
Security and Maintenance
Throughout its lifecycle, MariaDB 5.5 received numerous security fixes for various CVEs. Many performance schema and replication improvements also helped make the server more stable and secure in production environments.
FAQ
What is the main highlight of MariaDB 5.5?
The significantly improved thread pool and the new LIMIT ROWS EXAMINED optimization are among the most important performance enhancements.
Was MariaDB 5.5 a long-term support release?
Yes. It was an LTS release that received updates for many years, with the final release in May 2020.
What is the default storage engine in MariaDB 5.5?
XtraDB is the default storage engine, but you can switch to standard InnoDB using configuration options.
Does MariaDB 5.5 support vector search or modern AI features?
No. Vector data type and vector indexing were introduced much later in MariaDB 11.8.
Is MariaDB 5.5 still recommended for new projects?
No. MariaDB 5.5 reached end of support in 2020. It is recommended to upgrade to a newer LTS version such as 10.11, 11.4, or 11.8 for security updates and modern features.