The configuration management capability allows users of Cloud Databases to override the default database engine configuration settings provided by the Cloud Databases service.
A configuration group is a collection of key/value pairs, where the valid key/values are defined in the MySQL manual at http://dev.mysql.com/doc/refman/5.6/en/server-system-variables.html. Some directives are capable of being applied dynamically, while other directives require a server restart to take effect.
A default configuration group is applied to an instance if you create an instance without associating the instance with a configuration group. The default configuration is based upon the database engine and the instance flavor. If you want your database instance to run with custom defined configuration settings, you need to assign a custom defined configuration group to the instance. A configuration group can be applied to multiple instances.
You can create a new configuration group, modify parameters of an existing configuration group, and also modify the database instance to use a different configuration group. When a configuration group is modified either by way of adding a new key/value pair or modifying an existing key/value pair, the service updates the overrides.cnf file for every instance that is associated with the configuration.
The service attempts to dynamically update all associated database instances if the parameters changed in the configuration group are all dynamic. But if any of the parameters changed in the configuration group require a restart, then any instance that has the configuration group assigned to it will require a restart to apply the configuration group or any changes made to the configuration group.
Rackspace configures the validation rules for key/value pairs that can be assigned to a configuration group. These rules can be retrieved by the user from the API through the configuration parameter's resource as described in Configuration parameters.
Refer to Configurations for the API operations for configurations.