Hi, I explain you why... I have (to make it simple) 3 tables linked to eachother: -people: information about participants -peopcont: contests in which every people is registered -peopcontscore: score by contest by people (every contest can have more than one track and can then have many different scores) The joints have consistency check enabled. This means that when I delete one people, sql server also deletes related records in the two other tables. When I try doing so, i get following message: The query has been canceled because the estimated cost of this query (7671) exceeds the configured threshold of 300. Contact the system administrator. I have looked at the execution plan and it appears that the reason why this query is so expensive is because it needs to delete an index (peopcontid) on the peopcontscore table. The cost of sorting the records by this index is of 98% of the total cost!!! When I remove the index, the delete operation can occur. The problem is that I don't want to remove this index as it is frequently used in select statements. What can I do? Many thanks in advance, Nicolas.