mysqltuner

About mysqltuner

From Debian's package description

High-performance MySQL tuning script written in perl that will provide you with a snapshot of a MySQL server?s health. Based on the statistics gathered, specific recommendations will be provided that will increase a MySQL server's efficiency and performance. The script gives you automated MySQL tuning that is on the level of what you would receive from a MySQL DBA.

Features:

• Memory Usage: Calculates MySQL memory usage at max load and makes recommendations for increasing or decreasing the MySQL memory footprint. Per-thread and server-wide buffer data is calculated separately for an accurate snapshot of the server?s configuration.
• Slow Queries: Reviews the amount of slow queries relative to the total queries. Slow query time limits are also analyzed and recommendations are made.
• Connections: Current and historical connection counts are reviewed.
• Key Buffer: Takes configuration data and compares it to the actual indexes found in MyISAM tables. Key cache hit rates are calculated and variable adjustments are suggested.
• Query Cache: Query cache hit rates and usage percentages are used to make recommendations for the query cache configuration variables.
• Sorting & Joins: Per-thread buffers that affect sorts and joins are reviewed along with the statistics from the queries run against the server.
• Temporary Tables: Variable recommendations are made to reduce temporary tables that are written to the disk.
• Table Cache: Compares total tables opened to the currently open tables. Calculates the table cache hit rate in order to make suggestions.
• Open Files: Determines if the server will approach or run into the open file limit set by the operating system or the MySQL server itself.
• Table Locks: Finds table locking that forces queries to wait and makes suggestions for reducing locks that require a wait.
• Thread Cache: Calculates how many times MySQL must create a new thread to respond to a query.
• Aborted Connections: Finds applications that are not closing connections to MySQL properly.
• Read/Write Ratios: Calculates the percentage of read and write operations on your MySQL installation.

From Debian's description of the mysqltuner package, under that package's license.