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Azure SQL Database Resource Governance

Updated: March 12, 2015

This topic provides information about the request denial/connection loss mechanism due to governance on worker threads (max concurrent requests) and sessions.

The following table provides information about the request denial/connection loss mechanism due to governance on worker threads, the corresponding error code that is returned, and recommendation on how to address it.

 

Request Denial/Connection Loss Mechanism Error code returned Recommendation

SQL Database governs the limit on the number of worker threads (concurrent requests) to a database. Any database with more than the allowed limit of concurrent requests will receive error 10928, and further requests on this database can be denied.

  • For Web/Business edition database, the maximum limit of concurrent requests is 180. Beyond this limit, you will receive error 10928.

    Also, this limit (180) is only a maximum cap, and there is no guarantee that a Web/Business edition database will get requests up to this limit if the system is too busy. In case the system is too busy, it is possible that even fewer worker threads are available for the Web/Business edition database and user will receive error 10929. This is expected to be a rare occurrence.




    For Basic, Standard, and Premium databases, the concurrent request limit varies depending on the performance level of the database. For details, see Azure SQL Database Service Tiers and Performance Levels.

10928: Resource ID: 1. The %s limit for the database is %d and has been reached. See http://go.microsoft.com/fwlink/?LinkId=267637 for assistance.

10929: Resource ID: 1. The %s minimum guarantee is %d, maximum limit is %d and the current usage for the database is %d. However, the server is currently too busy to support requests greater than %d for this database. See http://go.microsoft.com/fwlink/?LinkId=267637 for assistance. Otherwise, please try again later.

noteNote
The Resource ID value in both the error messages indicates the resource for which limit has been reached. For worker threads, Resource ID = 1.

10928: Check dm_exec_requests to view which user requests are currently executing.

10929: Back-off and retry request after 10 seconds.

ImportantImportant
  • Errors due to governance on worker threads (10928/10929) replace the original engine throttling error (40501) for worker threads. Under normal conditions, users should no longer receive engine throttling error for worker threads.

  • In certain scenarios like the usage of federated database feature, it is possible to hit the worker thread cap error (10928) at the time of signing in to a database as this operation would utilize a worker thread underneath Connection.Open call. This may put the application above the worker thread cap threshold. Applications should have built-in logic to handle this error appropriately to handle such cases.

The following table provides information about the request denial/connection loss mechanism due to governance on sessions, the corresponding error code that is returned, and recommendation on how to address it.

 

Request Denial/Connection Loss Mechanism Error code returned Recommendation

SQL Database governs the limit on the number of concurrent sessions that can be established to a database. When concurrent session limit for a database is reached, new connections to the database are denied and user will receive error code 10928. However, the existing sessions to the database are not terminated.

  • For Web/Business edition database, the concurrent session limit is internal.

  • For Basic, Standard, and Premium databases, the concurrent sessions limit varies depending on the performance level of the database. For details, see Azure SQL Database Service Tiers and Performance Levels.

10928: Resource ID: 2. The %s limit for the database is %d and has been reached. See http://go.microsoft.com/fwlink/?LinkId=267637 for assistance.

noteNote
The Resource ID value in the error message indicates the resource for which limit has been reached. For sessions, Resource ID = 2.

10928: Check dm_exec_requests to view which user requests are currently executing.

See Also

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