MySQL 9.5: What's New, Release History & Support Lifecycle

What is New in MySQL 9.5

MySQL 9.5 is an Innovation release that brings practical improvements across security, performance, manageability, and modern development features. This version strengthens default security settings, enhances threading and logging efficiency, and adds useful tools for diagnostics and JavaScript support.

The updates focus on making the server more secure by default, easier to operate in containerized or high-load environments, and better equipped for analytical workloads while cleaning up older components.

Security and Authentication Enhancements

Security defaults have been raised in several areas. The number of digest rounds for caching_sha2_password now defaults to 10,000, providing stronger password hashing. Replication connections are now encrypted by default with SOURCE_SSL=1 and group_replication_ssl_mode=REQUIRED.

SCRAM-SHA-1 authentication has been deprecated in favor of SCRAM-SHA-256, which is now the default for SASL LDAP. The keyring_okv plugin is deprecated and replaced by the component_keyring_kmip component, which adds support for SECRET key types on newer Oracle Key Vault versions.

Performance and Configuration Improvements

Several defaults have been tuned for better real-world performance:

• binlog_transaction_dependency_history_size increased significantly to support larger transactions more efficiently.
• innodb_change_buffering now defaults to ALL, improving secondary index updates.
• innodb_log_writer_threads adjusts dynamically based on binary logging status and CPU count.

The thread pool plugin now includes automatic hardware-based tuning. It detects the number of vCPUs and intelligently sets thread_pool_size along with related variables for optimal concurrency.

Account Management and Connection Control

A new system variable activate_mandatory_roles gives administrators finer control over when mandatory roles are activated for user sessions.

The connection control component introduces component_connection_control.exempt_unknown_users, which helps load balancers and proxy setups by exempting unknown users from connection delay penalties. A corresponding status variable tracks these exempted connections.

JavaScript and JSON Enhancements

JavaScript stored procedures (using the Multi-Language Extension) now support larger result sets and fully comply with the ECMAScript 2025 standard. The mle.memory_max variable is automatically configured based on available physical memory.

JSON handling has been refined with fixes for high-precision floating point numbers and TIME value serialization. JSON Duality Views include better protection against accidental deletion of nested sub-objects.

New Tools and Diagnostic Features

A new Enterprise Edition tool called **MySQL Diagnostic Monitor** (mysqldm) has been introduced. It collects comprehensive server diagnostics and outputs them in JSON format, making troubleshooting and monitoring more convenient for administrators.

The explain_format default has changed to TREE, providing clearer and more readable query execution plans by default.

Deprecations and Removals

Several older items have been cleaned up to simplify maintenance:

• Old semisynchronous replication plugins (semisync_master and semisync_slave) have been removed in favor of the new source/replica naming.
• group_replication_allow_local_lower_version_join has been removed.
• Legacy replication variables such as replica_parallel_type are no longer available.

These changes encourage the use of modern, more consistent terminology and features across the server.

Other Notable Updates

The sys schema now includes a helpful procedure revoke_schema_privileges_from_all_accounts_except() for bulk privilege management. Various fixes have been applied to the optimizer, Performance Schema, and InnoDB to improve stability and correctness in edge cases.

Overall, MySQL 9.5 delivers a balanced set of enhancements that improve day-to-day operations, security posture, and developer experience while preparing the server for future scalability needs.