We are pleased to announce that telemetry is now available in Azure Monitor activity log to identify the causes of auto-resuming serverless workloads in Azure SQL Database. Prior to exposing this telemetry, the correlation of specific auto-resume causes with database activity could be time consuming and imperfect with no programmatic solution.
Serverless auto-pausing and auto-resuming
Serverless in SQL Database automatically scales compute based on workload demand and bills for compute used per second. In the General Purpose tier, serverless also provides an option to automatically pause the database during idle usage periods when only storage related costs are billed. The more a database is idle, the more auto-pausing can help reduce compute costs.
Automatic resuming occurs when database activity returns or certain management related or system operations are performed. Some examples of auto-resume triggers include logins, vulnerability assessment, modification to security settings like data masking rules, and service updates. A comprehensive description of auto-resume triggers is documented in the learning reference for serverless.
Activity log for auto-pause and auto-resume events
The Azure Monitor activity log keeps a record of all auto-pause and auto-resume events for serverless databases. Auto-resume causes are reported in activity log for "Resume Databases" operations under the “Caller” property of the "Succeeded" event, and latencies for each event are reported under “EventProperties”. This event can be monitored to quickly and deterministically identify auto-resume causes without resorting to inefficient guesswork.
Example of Activity log in Azure portal showing an auto-resume event including the cause and latency
In this example, the serverless database is auto-resumed in around 38 seconds in order to perform a security related vulnerability assessment.
Understanding the causes of auto-resuming can help in optimizing database access patterns to minimize auto-resume occurrences, keep the database paused for longer, and reduce compute costs even further.
Learn more
For more information, please see Azure SQL Database serverless and Azure Monitor activity log.
Microsoft