TechNote (Archived)

Behavior of cached queries when maximum number is set to 0

Issue

Cached queries within Macromedia ColdFusion MX are used to retrieve data result sets from server memory rather than through a database transaction. Because cached queries are stored in server memory, the ColdFusion Administrator allows a user imposed limit to the number of queries that are cached.

This value is set on the Caching page of the ColdFusion Administrator by providing a numeric value in the field "Maximum number of cached queries n". The default value for the setting is "100". Entering a "0" in this field is the same as defining the maximum number of cached queries as "unlimited". A "0" entered here causes ColdFusion to impose no limit to the maximum number of queries stored in server memory. In large applications where many queries are cached, not limiting the maximum number can cause CPU spikes and performance slowdowns as the amount of memory used increases over time.

Solution

Specify a maximum number of cached queries value in the ColdFusion Administrator. The number chosen depends on the amount of physical memory available and the number of queries that are likely to be cached by your application during peak load.