Open BOL 2005 and search for 'query governor'. However I would first look into why query takes so long to run and maybe there're ways to optimize it.

>
>When running a query I got the message
>
>'The query has been canceled because the estimated cost of this query (445) exceeds the configured threshold of 300.'
>
>Is that possible to change this value? Where?
>What are the implications to the overall performance ?
>
>TIA