In this conversation, the focus is on how the UPDLOCK (update lock) can cause serious performance issues, specifically excessive wait times and blocking in SQL Server. At Stedman Solutions, while working with a Managed Services client, we encountered a situation where SELECT statements were incorrectly using the UPDLOCK hint. Normally, update locks are intended for UPDATE operations, ensuring that no other transactions can modify the data during the operation. However, when applied to a SELECT query, the lock prevents other queries from accessing the same data, leading to substantial blocking and longer wait times.
The impact of using UPDLOCK in SELECT statements was significant—it essentially caused as much blocking as an actual update operation would have. This led to resource contention, where other queries were unable to access the locked rows or tables, resulting in slowdowns across the entire system. Since the locks remained active until the transaction completed, it caused bottlenecks, with subsequent queries having to wait for access to the same resources. As a result, system performance degraded considerably, with longer wait times and an overall reduction in efficiency.
Once we identified this improper use of UPDLOCK, we worked with the client to remove the HINT from the SELECT statements. The result was immediate and profound: performance improved significantly as the blocking was eliminated, and the overall resource utilization of the SQL Server returned to normal. This case highlights how crucial it is to understand the proper use of locking mechanisms in SQL Server, and how small misconfigurations like this can lead to large-scale performance issues.
Identifying such issues can be challenging, especially since UPDLOCK isn’t always easily visible or flagged as a problem unless you’re specifically looking for it. This is where monitoring tools like Database Health Monitor come in handy. Database Health Monitor allows for detailed performance tracking and can alert you to hidden issues like improper use of locking mechanisms, blocking, and excessive wait times. By continuously monitoring your SQL Server environment, you can catch these kinds of problems early and take corrective actions before they escalate into more serious performance bottlenecks.
For ongoing SQL Server management and Performance Tuning, Stedman Solutions’ Managed Services can help detect, diagnose, and resolve issues like this, ensuring your databases run efficiently. Our Team of SQL Server experts provides continuous monitoring and support to keep your environment optimized. Learn more about our managed services and how we can help maintain your SQL Server Performance at its best.
Contact Info
Stedman Solutions, LLC.PO Box 3175
Ferndale WA 98248
Phone: (360)610-7833