Are you experiencing performance bottlenecks? Is this query taking forever to complete? Most DBAs would start their resolution attempts with one of SQL Server’s most powerful features – Indexes. Indexes are such an effective mean that a small change could mean a world of a difference in performance. Most DBAs are also aware that adding indexes will cause some degradation of data modification operations as more indexes need to be updated to reflect the changes. However, few are aware that sometimes adding indexes can be a double-edged sword, with far reaching implications on performance, and not always for the best… This article will help you understand a hidden danger of adding more indexes, that can result in surprising effects on your workload. It tells a story of a production server that was brought to its knees with the addition of a single, innocent looking index.