Compatibility and Breaking Changes for MariaDB Enterprise Server 10.5

Guide Overview

This page acts as a technical reference, highlighting the logical impacts, architectural changes, and potential breaking points when upgrading to MariaDB Enterprise Server 10.5. It focuses on technical issues identified through customer support and engineering audits. This guide aims to supplement the comprehensive feature summaries available in the What's New in MariaDB Enterprise Server 10.5 page for MariaDB Enterprise Server 10.5.

For a full rundown of new features and overall improvements, users should consult the What's New guide. Note that for better clarity and accessibility, the technical specifics here may be integrated into the What's New guide in future documentation updates.

Architectural Changes

Binary and Process Renaming

MariaDB Enterprise Server 10.5 completes the transition to MariaDB-prefixed names for all executables.

• Process Identification: While symbolic links (e.g., mysqld) are provided for backward compatibility, the primary server binary is now mariadbd.

• Monitoring Alert: When started via systemd or mariadbd-safe, the process will identify as mariadbd in the system process list.

• Impact: Custom monitoring scripts using ps, pidof, or pgrep to look for mysqld will fail and must be updated to look for mariadbd.

Security and Privileges

Granularity (The "SUPER" Split)

In 10.5, the SUPER privilege has been deconstructed into several smaller, granular privileges to improve security.

Command / Operation	Legacy Privilege (10.4)	New Required Privilege (10.5)
SHOW REPLICA STATUS	REPLICATION CLIENT	REPLICA MONITOR
SHOW BINLOG EVENTS	REPLICATION SLAVE	BINLOG MONITOR
SHOW SLAVE HOSTS	REPLICATION CLIENT	REPLICATION MASTER ADMIN
PURGE BINARY LOGS	SUPER	BINLOG ADMIN

Configuration and Include Paths

Debian and Ubuntu Path Logic

Beginning with 10.5, the configuration loading logic on Debian and Ubuntu has shifted:

• Directory Priority: The directory /etc/mysql/mariadb.conf.d/ now uses numeric prefixes to dictate loading order.

• Enterprise Overrides: The mariadb-enterprise.cnf file is typically loaded last, potentially overriding user-defined settings in 50-server.cnf.

Pre-Upgrade Requirements

Mandatory Clean Shutdown

Upgrading from 10.4 to 10.5 after a crash is not supported if the redo log was created in 10.4.

• Requirement: You must perform a clean shutdown (setting SET GLOBAL innodb_fast_shutdown = 0 is recommended) before initiating the upgrade.

• Redo Log Adjustment: If innodb-log-files-in-group is set to 2, it must be changed to 1 on the 10.4 instance, followed by a restart and a final clean shutdown before moving to 10.5.

Critical Parameter Shifts

Parameter	10.4 Default	10.5 Default	Impact
innodb_adaptive_hash_index	ON	OFF	Disabled to prevent potential performance issues.
innodb_change_buffering	all	none	"all" was found to cause performance loss in certain workloads.
innodb_log_files_in_group	2	1	Redo logs are no longer split; additional files are ignored.
innodb_buffer_pool_instances	8	1	Multiple instances no longer reduce contention and are ignored.
slave_parallel_mode	conservative	optimistic	Speeds up replication by default.