Επεξεργασία

Κοινή χρήση μέσω

Troubleshoot issues and performance with SqlPackage

  • Άρθρο

In some scenarios, SqlPackage operations take longer than expected or fail to complete. This article describes some frequently suggested tactics to troubleshoot or improve performance of these operations. While reading the specific documentation page for each action to understand the available parameters and properties is recommended, this article serves as a starting point in investigating SqlPackage operations.

Overall strategy

As general guideline, better performance can be obtained via the .NET version of SqlPackage instead of the .NET Framework version installed via the DacFramework.msi.

If you're unable to install the SqlPackage dotnet tool, which enables executing SqlPackage commands from the command prompt in any directory:

  1. Download the zip for SqlPackage on .NET 8 for your operating system (Windows, macOS, or Linux).
  2. Unzip archive as directed on the download page.
  3. Open a command prompt and change directory (cd) to the SqlPackage folder.

It's important to use the latest available version of SqlPackage as performance improvements and bug fixes are released regularly.

Substitute SqlPackage for the Import/Export Service

If you attempted to use the Import/Export Service to import or export your database, you can use SqlPackage to perform the same operation with more control on optional parameters and properties.

For Import, an example command is:

./SqlPackage /Action:Import /sf:<source-bacpac-file-path> /tsn:<full-target-server-name> /tdn:<a new or empty database> /tu:<target-server-username> /tp:<target-server-password> /df:<log-file>

For Export, an example command is:

./SqlPackage /Action:Export /tf:<target-bacpac-file-path> /ssn:<full-source-server-name> /sdn:<source-database-name> /su:<source-server-username> /sp:<source-server-password> /df:<log-file>

Alternative to username and password, multifactor authentication can be used to authenticate via Microsoft Entra authentication (formerly Azure Active Directory) with multifactor authentication. Substitute the username and password parameters for /ua:true and /tid:"yourdomain.onmicrosoft.com".

Common issues

Timeout errors

For issues related to timeouts, the following properties can be used to tune the connection between SqlPackage and the SQL instance:

  • /p:CommandTimeout=: Specifies the command timeout in seconds when a query is executed. Default: 60
  • /p:DatabaseLockTimeout=: Specifies the database lock timeout in seconds. -1 can be used to wait indefinitely, default: 60
  • /p:LongRunningCommandTimeout=: Specifies the long running command timeout in seconds. The default value, 0, is used to wait indefinitely.

Client resource consumption

For the export and extract commands, table data is passed to a temporary directory to buffer before being written to the bacpac/dacpac file. This storage requirement can be large and is relative to the full size of the data to be exported. Specify an alternative temporary directory with the property /p:TempDirectoryForTableData=<path>.

The schema model is compiled in memory, so for large database schemas the memory requirement on the client machine running SqlPackage can be significant.

Low server resource consumption

By default, SqlPackage sets the maximum server parallelism to 8. If you note low server resource consumption, increasing the value of the MaxParallelism parameter can improve performance.

Access token

Using the /AccessToken: or /at: parameter enables token-based authentication for SqlPackage, however passing the token to the command can be tricky. If you're parsing an access token object in PowerShell, either explicitly pass the string value or wrap the reference to the token property in $(). For example:

$Account = Connect-AzAccount -ServicePrincipal -Tenant $Tenant -Credential $Credential
$AccessToken_Object = (Get-AzAccessToken -Account $Account -Resource "https://database.windows.net/")
$AccessToken = $AccessToken_Object.Token

SqlPackage /at:$AccessToken
# OR
SqlPackage /at:$($AccessToken_Object.Token)

Connection

If SqlPackage is failing to connect, the server might not have encryption enabled or the configured certificate might not be issued from a trusted certificate authority (such as a self-signed certificate). You can change the SqlPackage command to either connect without encryption or to trust the server certificate. The best practice is to ensure that a trusted encrypted connection to the server can be established.

  • Connect without encryption: /SourceEncryptConnection:False or /TargetEncryptConnection:False
  • Trust server certificate: /SourceTrustServerCertificate:True or /TargetTrustServerCertificate:True

You could see any of the following warning messages when connecting to a SQL instance, indicating that command line parameters could require changes to connect to the server:

The settings for connection encryption or server certificate trust may lead to connection failure if the server is not properly configured.
The connection string provided contains encryption settings which may lead to connection failure if the server is not properly configured.

More information about the connection security changes in SqlPackage is available in Connection Security Improvements in SqlPackage 161.

Import action error 2714 for constraint

When performing an import action, you might receive error 2714 if an object already exists:

*** Error importing database:Could not import package.
Error SQL72014: Core Microsoft SqlClient Data Provider: Msg 2714, Level 16, State 5, Line 1 There is already an object named 'DF_Department_ModifiedDate_0FF0B724' in the database.
Error SQL72045: Script execution error. The executed script:
ALTER TABLE [HumanResources].[Department]
    ADD CONSTRAINT [DF_Department_ModifiedDate_] DEFAULT ('') FOR [ModifiedDate];

Here are the causes and solutions to work around this error:

  1. Verify that the destination you're importing into is an empty database.
  2. If your database has constraints that are using the DEFAULT attribute (where SQL Server assigns a random name to the constraint) and an explicitly named constraint, a constraint with the same name might be created twice. You should use all explicitly named constraints (not using DEFAULT), or all system-defined names (using DEFAULT).
  3. Manually edit the model.xml and rename the constraint with the name experiencing the error to a unique name. This option should be undertaken only if directed by Microsoft support and poses a risk of .bacpac corruption.

Stack overflow exception

Large T-SQL scripts with many nested statements are often the cause of intermittent or persistent stack overflow exceptions. When this is the case, the error message will include the text Stack overflow and a stack trace of:

Microsoft.SqlServer.TransactSql.ScriptDom.TSqlFragmentVisitor.Visit(Microsoft.SqlServer.TransactSql.ScriptDom.BinaryQueryExpression)
Microsoft.SqlServer.TransactSql.ScriptDom.TSqlFragmentVisitor.ExplicitVisit(Microsoft.SqlServer.TransactSql.ScriptDom.BinaryQueryExpression)
Microsoft.SqlServer.TransactSql.ScriptDom.BinaryQueryExpression.Accept(Microsoft.SqlServer.TransactSql.ScriptDom.TSqlFragmentVisitor)
Microsoft.SqlServer.TransactSql.ScriptDom.BinaryQueryExpression.AcceptChildren(Microsoft.SqlServer.TransactSql.ScriptDom.TSqlFragmentVisitor)
Microsoft.SqlServer.TransactSql.ScriptDom.BinaryQueryExpression.Accept(Microsoft.SqlServer.TransactSql.ScriptDom.TSqlFragmentVisitor)
Microsoft.SqlServer.TransactSql.ScriptDom.BinaryQueryExpression.AcceptChildren(Microsoft.SqlServer.TransactSql.ScriptDom.TSqlFragmentVisitor)

A parameter for SqlPackage is available on all commands, /ThreadMaxStackSize:, which specifies the maximum stack size for the thread running the SqlPackage process. The default value is determined by the .NET version running SqlPackage. Setting a large value can impact overall performance of SqlPackage, however increasing this value might resolve the stack overflow exception caused by nested statements. Refactoring the T-SQL code is recommended to avoid stack overflow exceptions whenever possible, but the /ThreadMaxStackSize: parameter can be used as a workaround.

When using the /ThreadMaxStackSize: parameter, it's recommended to tune repeated operations to the lowest value that resolves the stack overflow exception if performance impact is noted. The value of the parameter is in megabytes (MB), example values for testing as a workaround include 10 and 100.

Diagnostics

Logs are essential to troubleshooting. Capture the diagnostic logs to a file with the /DiagnosticsFile:<filename> parameter.

More performance-related trace data can be logged by setting the environment variable DACFX_PERF_TRACE=true before running SqlPackage. To set this environment variable in PowerShell, use the following command:

Set-Item -Path Env:DACFX_PERF_TRACE -Value true

Import action tips

For imports that contain large tables or tables with many indexes, the use of /p:RebuildIndexesOfflineForDataPhase=True or /p:DisableIndexesForDataPhase=False can improve performance. These properties modify the index rebuild operation to occur offline or not occur, respectively. Those and other properties are available to tune the SqlPackage Import operation.

Export action tips

A common cause of performance degradation during export is unresolved object references, which causes SqlPackage to attempt to resolve the object multiple times. For example, a view is defined that references a table and the table no longer exists in the database. If unresolved references appear in the export log, consider correcting the schema of the database to improve the export performance.

In scenarios where the OS disk space is limited and runs out during the export, the use of /p:TempDirectoryForTableData allows the data for export to be buffered on an alternative disk. The space required for this action might be large and is relative to the full size of the database. That and other properties are available to tune the SqlPackage Export operation.

During an export process, the table data is compressed in the bacpac file. The use of /p:CompressionOption set to Fast, SuperFast, or NotCompressed might improve the export process speed while compressing the output bacpac file less.

To obtain the database schema and data while skipping the schema validation, perform an Export with the property /p:VerifyExtraction=False. An invalid export might be produced that can't be imported.

Azure SQL Database

The following tips are specific to running import or export against Azure SQL Database from an Azure virtual machine (VM):

  • Use Business Critical or Premium tier database for best performance.
  • Use SSD storage on the VM.
  • Ensure there's enough room to unzip the bacpac.
  • Execute SqlPackage from a VM in the same region as the database.
  • Enable accelerated networking in the VM.

For more information on utilizing a PowerShell script to collect more information about an import operation, see Lesson Learned #211: Monitoring SQLPackage Import Process.

More resources

The Azure Database Support Blog contains many articles on troubleshooting and performance tuning for Azure SQL Database, including several articles on SqlPackage.

Some of the most relevant articles include:

Related content