Microsoft® SQL Server 2012 Unleashed

Limiting Query Plan Execution with the Query Governor

Another tool for managing query plans in SQL Server 2012 is the query governor. Because SQL Server uses a cost-based Query Optimizer, the cost of executing a given query is always estimated before the query is actually executed. The query governor enables you to set a cost threshold to prevent certain long-running queries from being executed. This is not so much an optimization tuning tool as it is a performance problem prevention tool.

For example, if you have an application with an ad hoc reporting front end, you have no way of controlling what the user is going to request from the database and the type of query generated. The query governor allows you to prevent a runaway query from executing ...