SqlServerDeadlock #

SQL Server is having some deadlock.

Alert Rule

alert: SqlServerDeadlock
annotations:
  description: |-
    SQL Server is having some deadlock.
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/ozarklake-mssql-exporter/sqlserverdeadlock/
  summary: SQL Server deadlock (instance {{ $labels.instance }})
expr: increase(mssql_deadlocks[1m]) &gt; 5
for: 0m
labels:
  severity: warning

Here is a sample runbook for the SqlServerDeadlock alert:

Meaning #

A SQL Server deadlock occurs when two or more transactions are blocked, each waiting for the other to release a resource. This alert is triggered when the number of deadlocks in the last minute exceeds 5.

Impact #

Deadlocks can have a significant impact on the performance and availability of your SQL Server database. They can cause transactions to roll back, leading to data inconsistencies and errors. In extreme cases, deadlocks can even lead to database crashes or corruption.

Diagnosis #

To diagnose the root cause of the deadlock, follow these steps:

Check the SQL Server error log for deadlock events.
Identify the specific queries and transactions involved in the deadlock.
Analyze the query plans and execution statistics to understand the resource contention.
Review the database server configuration, including memory, CPU, and disk usage.
Check for any ongoing maintenance or maintenance tasks that may be contributing to the deadlock.

Mitigation #

To mitigate the deadlock, follow these steps:

Kill the affected transactions and rerun them when the deadlock is resolved.
Optimize the queries and database design to reduce resource contention.
Implement row-level locking or snapshot isolation to reduce the likelihood of deadlocks.
Monitor the database server resources and adjust the configuration as needed.
Consider implementing deadlock detection and automatic rollback mechanisms to minimize the impact of deadlocks.

Additional resources: