1. A database monitoring system that monitors performance of a database system in which database events having an execution code path are occurring, comprising: a collection of database system object types each having at least one object attribute that corresponds to a property of the object type a rule engine that evaluates rules for taking action based on database system performance; wherein a rule is triggered by the occurrence of a database event and specifies a condition and an action to be taken by the monitoring system when the condition is met; and wherein the rule engine evaluates the condition and takes the specified action if the condition is met as part of the database event's execution code path.