How to get deadlocks history in SQL Server using system_health extended events?

This article helps to find

Deadlock history or How to get deadlocks history in SQL Server using system_health extended events?

Deadlock :

refers to a situation where two or more transactions are waiting for each other to release resources, resulting in a state of permanent blocking. This impasse prevents any of the transactions involved from progressing further, leading to a halt in the system’s operation.

A deadlock typically occurs when the following conditions are met:

1. Mutual Exclusion: Each transaction holds a resource exclusively that another transaction requires.
2. Hold and Wait: A transaction holds a resource while waiting to acquire additional resources.
3. No Preemption: Resources cannot be forcibly taken away from a transaction; they can only be released voluntarily.
4. Circular Wait: A circular chain of transactions exists, where each transaction is waiting for a resource held by another transaction in the chain.

This video helps to identify deadlock history or

How to get deadlocks history in SQL Server using system_health extended events?

Once you identify Deadlocks you can review those and take necessary action

SQL Server incorporates mechanisms to detect and resolve deadlocks. Upon detection, SQL Server automatically chooses one transaction as a victim and terminates it, allowing the other transaction(s) to proceed. The terminated transaction is then rolled back, ensuring data consistency.

To minimize the occurrence of deadlocks, developers and database administrators can take preventive measures. This includes optimizing query performance, reducing transaction duration, and using appropriate isolation levels. SQL Server also provides tools and techniques, such as deadlock graphs and lock monitoring, to aid in identifying and troubleshooting deadlock situations.