Unexpected Select queries seen in the Performance Overview of the Azure Portal


Scenario:
During a time of low database activity, you may see an unexpected spike of DTU consumption in the performance graphs on the Azure Portal. Drilling into it through the Performance Overview and Query Performance Insight feature, you identify some queries which you do not recognize. The overall DTU consumption for them is rather low though.

The queries have the following pattern, accessing one of your own user tables:

(@LowerBound int,@UpperBound int)SELECT   [ID],
   [column_1],
   [column_2],
   ...,
   [column_n]
FROM     [dbo].[yourtablename]
WHERE    [ID] >= @LowerBound
AND [ID] < @UpperBound
ORDER BY [ID] ASC

Explanation:

This type of query is related to exporting an Azure SQL Database into a BACPAC file. You may see it after running either of the following:

  • Selecting "Export Data-tier Application" from the database context menu in SQL Server Management Studio
  • Running the SQLPACKAGE.EXE command line tool from C:\Program Files (x86)\Microsoft SQL Server\130\DAC\bin
  • Calling the Export method of the Microsoft.SqlServer.Management.Dac.DacStore type in a .Net Framework application
  • Calling the REST API of the DACWebService.svc service, available through the Data-Tier Application Framework (DACFx)

Either of these may be executed by a manual or scheduled process, or by any tool that is providing export or backup functionality for Azure SQL Database.

Further References:

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