Understanding Blocking vs. Deadlocks

What It Is

Blocking is when one process holds a lock another needs. Deadlocks occur when two or more processes block each other permanently.

Why It Matters

• Blocking slows performance, but resolves itself.
• Deadlocks require SQL Server to terminate one process.

How to Spot It

• Use SQL Profiler or Extended Events.
• Monitor deadlock graphs and blocking chains.
• Real-time alerts via SQL Diagnostic Manager.

How to Fix or Address It

• Optimize query order and indexing.
• Use WITH (NOLOCK) cautiously.
• Implement deadlock retry logic in apps.

Key Takeaway

Not all locking is bad—but understanding blocking and deadlocks prevents downtime and frustration.

How Can Idera Help?

Identify and resolve lock issues faster by using SQL Diagnostic Manager. For more information or to start a free trial, visit us HERE.