Database Version Rift Skill

Description

This skill maps critical differences between MySQL and MariaDB versions to help developers implement cross-compatible diagnostics in MySQLTuner.

Replication Commands

Feature	MySQL < 8.0.22 / MariaDB < 10.5	MySQL >= 8.0.22	MariaDB >= 10.5
Show Slave Status	`SHOW SLAVE STATUS`	`SHOW REPLICA STATUS` (Preferred)	`SHOW REPLICA STATUS` (Preferred)
Show Slave Hosts	`SHOW SLAVE HOSTS`	`SHOW REPLICA HOSTS`	`SHOW REPLICA HOSTS`

Strategy: Detect version first. If version >= breakpoint, try REPLICA, fall back to SLAVE if error or empty (though strictly version check is safer).

Authentication & Security

Feature	MySQL 5.7 / MariaDB	MySQL 8.0+
PASSWORD() function	Available	REMOVED (Use SHA2 functions or app-side hashing)
User table	`mysql.user` (authentication_string since 5.7)	`mysql.user` (authentication_string)

Strategy: For password checks in MySQL 8.0+, do strictly SQL-based checks (e.g., length of auth string) or avoid logic that depends on hashing input strings via SQL.

Information Schema Differences

`information_schema.TABLES`

•Usually stable, but check Data_free interpretation across engines.

`performance_schema`

•MySQL 5.6+: Defaults enabled (mostly).
•MariaDB 10.0+: Defaults varying.
•Check: Always verify performance_schema = ON before querying tables.

System Variables (Renames)

Legacy Name	Modern Name (MySQL 8.0+)	Note
`tx_isolation`	`transaction_isolation`	Check both or `
`query_cache_size`	Removed	Removed in MySQL 8.0

Strategy: Use the mysqltuner.pl valid variable abstraction or check for existence before using.

MariaDB vs MySQL Divergence

•
Thread Pool:
- •MariaDB: Built-in, specific vars (thread_pool_size, thread_pool_oversubscribe).
- •MySQL: Enterprise only or Percona specific.
- •Action: Check version_comment or version string for "MariaDB" before recommending thread pool settings.
•
Aria Engine:
- •Specific to MariaDB (replacement for MyISAM for system tables).
- •Don't tune aria_pagecache_buffer_size on Oracle MySQL.