Quick Scan Report – Deadlocks

What Is a Deadlock in SQL Server?

A deadlock occurs when two or more processes hold locks on resources that the other needs, creating a circular wait condition where neither can proceed. SQL Server automatically detects deadlocks and chooses a victim process to terminate, rolling back its transaction to break the cycle.

Example of a Deadlock

  1. Transaction A locks Table1 and needs access to Table2.
  2. Transaction B locks Table2 and needs access to Table1.
  3. Both transactions wait for the other to release the lock, causing an indefinite wait.
  4. SQL Server detects the deadlock and terminates one of the transactions to allow the other to proceed.

Why Deadlocks Are a Problem

  • Transaction Rollbacks: One transaction is always terminated, leading to data consistency issues.
  • Application Errors: Users may experience errors if a transaction is chosen as the deadlock victim.
  • Performance Slowdowns: Frequent deadlocks cause repeated transaction retries, reducing system efficiency.

How to Prevent Deadlocks

  • Use a Consistent Locking Order: Ensure all transactions access tables in the same order.
  • Keep Transactions Short: Reduce the time locks are held by committing transactions quickly.
  • Optimize Indexing: Proper indexing can minimize lock contention.
  • Use Read Committed Snapshot Isolation (RCSI): Reduces locking conflicts by enabling row versioning.

Monitor and Detect Deadlocks with Database Health Monitor

Check out our blog post on Deadlocks to learn more!

Need Expert Help?

Frequent deadlocks may indicate deeper performance issues. Stedman Solutions’ SQL Server Managed Services can help tune your queries, optimize indexes, and reduce contention.

Contact Stedman Solutions Today for expert SQL Server troubleshooting!