Spotlight on Oracle 10.5 - Release Notes

Query Cache Hit Rate Alarm

The MySQL query cache stores the most recent SELECT queries performed by the MySQL database server, together with the result sets of those queries. This can reduce much of the parsing overhead, and logical or physical I/O, associated with those queries if and when the queries are repeated.

The Query Cache Hit Rate alarm fires when the proportion of SQL queries that can be found in the MySQL query cache drops below a specified threshold.

You may be able to tune the performance of the query cache by modifying configuration variables to:

• Change the size or type of the query cache.
• Change the maximum size of queries that can be cached.
• Change the allocation size or minimum block size for cached queries.

Related Topics

MySQL Reference Manual