SQL Data Sync | Snapshot isolation transaction failed accessing database '***' because snapshot isolation is not allowed in this database.

Manivannan Sivaraj 0

Hi,

I'm setting up a SQL Data sync using PowerShell following this article: https://learn.microsoft.com/en-us/azure/azure-sql/database/scripts/sql-data-sync-sync-data-between-sql-databases?view=azuresql-db

Sync Hub is an Azure SQL Database. Sync Member is also an Azure SQL Database. Both the databases are in the same sql server (Azure).

When I start sync operation (using the command 'Start-AzSqlSyncGroupSync'), it fails with the message that Hub database does not allow snapshot isolation. And, recommended to alter DB to ALLOW_SNAPSHOT_ISOLATION.

Actual Error message: Snapshot isolation transaction failed accessing database <DBName> because snapshot isolation is not allowed in this database. Use ALTER DATABASE to allow snapshot isolation. For more information, provide tracing ID to customer support.

So, I ran the following queries against both hub and member databases to turn on snapshot isolation:

ALTER DATABASE [DB name] 
SET ALLOW_SNAPSHOT_ISOLATION ON
  
ALTER DATABASE [DB name] 
SET READ_COMMITTED_SNAPSHOT ON

I'm still getting the same error though. Any suggestions please?

Oury Ba-MSFT 18,021 Reputation points Microsoft Employee

2023-07-31T23:00:59.73+00:00

@Manivannan Sivaraj Thank you for reaching out.

My understanding is that you are trying to a data sync but getting an error message which stated that "Snapshot isolation transaction failed accessing database <DBName> because snapshot isolation is not allowed in this database. Use ALTER DATABASE to allow snapshot isolation. For more information, provide tracing ID to customer support."

Same issue was raised here https://learn.microsoft.com/en-us/answers/questions/598206/azure-sql-sync-failed-due-to-snapshot-isolation-in.

Customer who raised the issue were able to fix it by setting up all sync DB.

Tutorial: Set up SQL Data Sync between databases in Azure SQL Database and SQL Server

Pease let us know if the same resolution worked for you too. If it does not, please comment below so we can continue to work on the same.

Regards,

Oury
Manivannan Sivaraj 0 Reputation points

2023-08-01T15:07:53.1233333+00:00

Hi @Oury Ba-MSFT , Thanks for your response. I'm trying to setup sync through PowerShell. Though I setup snapshot isolation, it is getting reset. I think probably it should be somewhere within my script. I can take it from here. I'll update this page once I find the solution for it.

Oury Ba-MSFT 18,021 Microsoft Employee

Manivannan Sivaraj

I wanted to check if there is any progress on the above issue.

You can also go through this doc https://learn.microsoft.com/en-us/azure/azure-sql/database/scripts/sql-data-sync-sync-data-between-sql-databases?view=azuresql which has steps by steps on how to configures SQL Data Sync to sync data between multiple databases in Azure SQL Database using PowerShell script.

sample PowerShell script to create a data sync.

using namespace Microsoft.Azure.Commands.Sql.DataSync.Model
using namespace System.Collections.Generic

# hub database info
$subscriptionId = "<subscriptionId>"
$resourceGroupName = "<resourceGroupName>"
$serverName = "<serverName>"
$databaseName = "<databaseName>"

# sync database info
$syncDatabaseResourceGroupName = "<syncResourceGroupName>"
$syncDatabaseServerName = "<syncServerName>"
$syncDatabaseName = "<syncDatabaseName>"

# sync group info
$syncGroupName = "<syncGroupName>"
$conflictResolutionPolicy = "HubWin" # can be HubWin or MemberWin
$intervalInSeconds = 300 # sync interval in seconds (must be no less than 300)

# member database info
$syncMemberName = "<syncMemberName>"
$memberServerName = "<memberServerName>"
$memberDatabaseName = "<memberDatabaseName>"
$memberDatabaseType = "SqlServerDatabase" # can be AzureSqlDatabase or SqlServerDatabase
$syncDirection = "Bidirectional" # can be Bidirectional, Onewaymembertohub, Onewayhubtomember

# sync agent info
$syncAgentName = "<agentName>"
$syncAgentResourceGroupName = "<syncAgentResourceGroupName>"
$syncAgentServerName = "<syncAgentServerName>"

$syncMemberResourceId = "/subscriptions/$subscriptionId/resourceGroups/$resourceGroupName/providers/Microsoft.Sql/servers/$serverName/databases/$syncMemberDBName"

# temp file to save the sync schema
$tempFile = $env:TEMP+"\syncSchema.json"

# list of included columns and tables in quoted name
$includedColumnsAndTables =  "[SalesLT].[Address].[AddressID]",
                             "[SalesLT].[Address].[AddressLine2]",
                             "[SalesLT].[Address].[rowguid]",
                             "[SalesLT].[Address].[PostalCode]",
                             "[SalesLT].[ProductDescription]"
$metadataList = [System.Collections.ArrayList]::new($includedColumnsAndTables)

Connect-AzAccount
Select-AzSubscription -SubscriptionId $subscriptionId

# use if it's safe to show password in script, otherwise use PromptForCredential
# $user = "username"
# $password = ConvertTo-SecureString -String "password" -AsPlainText -Force
# $credential = New-Object -TypeName "System.Management.Automation.PSCredential" -ArgumentList $user, $password

$credential = $Host.ui.PromptForCredential("Need credential",
              "Please enter your user name and password for server "+$serverName+".database.windows.net",
              "",
              "")

# create a new sync group (if you use private link, make sure to manually approve it)
Write-Host "Creating Sync Group "$syncGroupName"..."
New-AzSqlSyncGroup -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName -Name $syncGroupName `
    -SyncDatabaseName $syncDatabaseName -SyncDatabaseServerName $syncDatabaseServerName -SyncDatabaseResourceGroupName $syncDatabaseResourceGroupName `
    -ConflictResolutionPolicy $conflictResolutionPolicy -DatabaseCredential $credential -UsePrivateLinkConnection | Format-list

# use if it's safe to show password in script, otherwise use PromptForCredential
# $user = "username"
# $password = ConvertTo-SecureString -String "password" -AsPlainText -Force
# $credential = New-Object -TypeName "System.Management.Automation.PSCredential" -ArgumentList $user, $password

$credential = $Host.ui.PromptForCredential("Need credential",
              "Please enter your user name and password for server "+$serverName+".database.windows.net",
              "",
              "")

# add a new sync member (if you use private link, make sure to manually approve it)
Write-Host "Adding member"$syncMemberName" to the sync group..."
New-AzSqlSyncMember -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName `
    -SyncGroupName $syncGroupName -Name $syncMemberName -MemberDatabaseType $memberDatabaseType -SyncAgentResourceGroupName $syncAgentResourceGroupName `
    -SyncAgentServerName $syncAgentServerName -SyncAgentName $syncAgentName  -SyncDirection $syncDirection -SqlServerDatabaseID  $syncAgentInfo.DatabaseId `
    -SyncMemberAzureDatabaseResourceId $syncMemberResourceId -UsePrivateLinkConnection | Format-list

# update existing sync member to use private link connection 
Update-AzSqlSyncMember `
    -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName -SyncGroupName $syncGroupName -Name $syncMemberName `
    -MemberDatabaseCredential $memberDatabaseCredential -SyncMemberAzureDatabaseResourceId $syncMemberResourceId -UsePrivateLinkConnection $true
    
# update existing sync group and remove private link connection
Update-AzSqlSyncGroup `
    -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName -Name $syncGroupName -UsePrivateLinkConnection $false

# run the following Get-AzSqlSyncGroup/ Get-AzSqlSyncMember commands to confirm that a private link has been setup for Data Sync, if you decide to use private link. 
# Get-AzSqlSyncMember returns information about one or more Azure SQL Database Sync Members. Specify the name of a sync member to see information for only that sync member.
Get-AzSqlSyncMember `
    -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName -SyncGroupName $syncGroupName -Name $syncMemberName ` | Format-List
# Get-AzSqlSyncGroup returns information about one or more Azure SQL Database Sync Groups. Specify the name of a sync group to see information for only that sync group.
Get-AzSqlSyncGroup `
    -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName ` | Format-List
    
# approve private endpoint connection, if you decide to use private link
Approve-AzPrivateEndpointConnection `
    -Name myPrivateEndpointConnection -ResourceGroupName myResourceGroup -ServiceName myPrivateLinkService

# refresh database schema from hub database, specify the -SyncMemberName parameter if you want to refresh schema from the member database
Write-Host "Refreshing database schema from hub database..."
$startTime = Get-Date
Update-AzSqlSyncSchema -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName -SyncGroupName $syncGroupName

# waiting for successful refresh
$startTime = $startTime.ToUniversalTime()
$timer=0
$timeout=90

# check the log and see if refresh has gone through
Write-Host "Check for successful refresh..."
$isSucceeded = $false
while ($isSucceeded -eq $false) {
    Start-Sleep -s 10
    $timer=$timer+10
    $details = Get-AzSqlSyncSchema -SyncGroupName $syncGroupName -ServerName $serverName -DatabaseName $databaseName -ResourceGroupName $resourceGroupName
    if ($details.LastUpdateTime -gt $startTime) {
        Write-Host "Refresh was successful"
        $isSucceeded = $true
    }
    if ($timer -eq $timeout) {
        Write-Host "Refresh timed out"
        break;
    }
}

# get the database schema
Write-Host "Adding tables and columns to the sync schema..."
$databaseSchema = Get-AzSqlSyncSchema -ResourceGroupName $ResourceGroupName -ServerName $ServerName `
    -DatabaseName $DatabaseName -SyncGroupName $SyncGroupName `

$databaseSchema | ConvertTo-Json -depth 5 -Compress | Out-File "C:\Users\OnPremiseServer\AppData\Local\Temp\syncSchema.json"

$newSchema = [AzureSqlSyncGroupSchemaModel]::new()
$newSchema.Tables = [List[AzureSqlSyncGroupSchemaTableModel]]::new();

# add columns and tables to the sync schema
foreach ($tableSchema in $databaseSchema.Tables) {
    $newTableSchema = [AzureSqlSyncGroupSchemaTableModel]::new()
    $newTableSchema.QuotedName = $tableSchema.QuotedName
    $newTableSchema.Columns = [List[AzureSqlSyncGroupSchemaColumnModel]]::new();
    $addAllColumns = $false
    if ($MetadataList.Contains($tableSchema.QuotedName)) {
        if ($tableSchema.HasError) {
            $fullTableName = $tableSchema.QuotedName
            Write-Host "Can't add table $fullTableName to the sync schema" -foregroundcolor "Red"
            Write-Host $tableSchema.ErrorId -foregroundcolor "Red"
            continue;
        }
        else {
            $addAllColumns = $true
        }
    }
    foreach($columnSchema in $tableSchema.Columns) {
        $fullColumnName = $tableSchema.QuotedName + "." + $columnSchema.QuotedName
        if ($addAllColumns -or $MetadataList.Contains($fullColumnName)) {
            if ((-not $addAllColumns) -and $tableSchema.HasError) {
                Write-Host "Can't add column $fullColumnName to the sync schema" -foregroundcolor "Red"
                Write-Host $tableSchema.ErrorId -foregroundcolor "Red"
            }
            elseif ((-not $addAllColumns) -and $columnSchema.HasError) {
                Write-Host "Can't add column $fullColumnName to the sync schema" -foregroundcolor "Red"
                Write-Host $columnSchema.ErrorId -foregroundcolor "Red"
            }
            else {
                Write-Host "Adding"$fullColumnName" to the sync schema"
                $newColumnSchema = [AzureSqlSyncGroupSchemaColumnModel]::new()
                $newColumnSchema.QuotedName = $columnSchema.QuotedName
                $newColumnSchema.DataSize = $columnSchema.DataSize
                $newColumnSchema.DataType = $columnSchema.DataType
                $newTableSchema.Columns.Add($newColumnSchema)
            }
        }
    }
    if ($newTableSchema.Columns.Count -gt 0) {
        $newSchema.Tables.Add($newTableSchema)
    }
}

# convert sync schema to JSON format
$schemaString = $newSchema | ConvertTo-Json -depth 5 -Compress

# work around a PowerShell bug
$schemaString = $schemaString.Replace('"Tables"', '"tables"').Replace('"Columns"', '"columns"').Replace('"QuotedName"', '"quotedName"').Replace('"MasterSyncMemberName"','"masterSyncMemberName"')

# save the sync schema to a temp file
$schemaString | Out-File $tempFile

# update sync schema
Write-Host "Updating the sync schema..."
Update-AzSqlSyncGroup -ResourceGroupName $resourceGroupName -ServerName $serverName `
    -DatabaseName $databaseName -Name $syncGroupName -Schema $tempFile

$syncLogStartTime = Get-Date

# trigger sync manually
Write-Host "Trigger sync manually..."
Start-AzSqlSyncGroupSync -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName -SyncGroupName $syncGroupName

# check the sync log and wait until the first sync succeeded
Write-Host "Check the sync log..."
$isSucceeded = $false
for ($i = 0; ($i -lt 300) -and (-not $isSucceeded); $i = $i + 10) {
    Start-Sleep -s 10
    $syncLogEndTime = Get-Date
    $syncLogList = Get-AzSqlSyncGroupLog -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName `
        -SyncGroupName $syncGroupName -StartTime $syncLogStartTime.ToUniversalTime() -EndTime $syncLogEndTime.ToUniversalTime()

    if ($synclogList.Length -gt 0) {
        foreach ($syncLog in $syncLogList) {
            if ($syncLog.Details.Contains("Sync completed successfully")) {
                Write-Host $syncLog.TimeStamp : $syncLog.Details
                $isSucceeded = $true
            }
        }
    }
}

if ($isSucceeded) {
    # enable scheduled sync
    Write-Host "Enable the scheduled sync with 300 seconds interval..."
    Update-AzSqlSyncGroup  -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName `
        -Name $syncGroupName -IntervalInSeconds $intervalInSeconds
}
else {
    # output all log if sync doesn't succeed in 300 seconds
    $syncLogEndTime = Get-Date
    $syncLogList = Get-AzSqlSyncGroupLog  -ResourceGroupName $resourceGroupName -ServerName $serverName -DatabaseName $databaseName `
        -SyncGroupName $syncGroupName -StartTime $syncLogStartTime.ToUniversalTime() -EndTime $syncLogEndTime.ToUniversalTime()

    if ($synclogList.Length -gt 0) {
        foreach ($syncLog in $syncLogList) {
            Write-Host $syncLog.TimeStamp : $syncLog.Details
        }
    }
}

Please let us know the result.

Regards,

Oury

Manivannan Sivaraj 0 Reputation points

2023-08-02T19:31:14.3366667+00:00

Hi @Oury Ba-MSFT , Yes, that is the link I followed. It worked now. Executing the command "ALTER DATABASE [DB name] SET ALLOW_SNAPSHOT_ISOLATION ON" on the hub database worked. I had a predecessor script that reset the snapshot_isolation flag back to OFF. Upon fixing it, sync happened successfully. Thanks for followed up.

2 answers

Manivannan Sivaraj 0 Reputation points

2023-08-02T19:32:44.08+00:00

Executing the command "ALTER DATABASE [DB name] SET ALLOW_SNAPSHOT_ISOLATION ON" on the hub database worked, and made the sync successful. We can mark this as resolved.
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Oury Ba-MSFT 18,021 Reputation points Microsoft Employee

2023-08-02T22:37:49.25+00:00

Manivannan Sivaraj

Thank you so much for letting me know. I am glad that fix the issue.

Regards,

Oury
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Oury Ba-MSFT 18,021 Reputation points Microsoft Employee

2023-08-02T22:41:14.8466667+00:00

@Manivannan Sivaraj Thank you for confirming issue is resolved.

Issue:

You were trying to do a data sync between 2 databases in the same Server but getting an error message which stated that "Snapshot isolation transaction failed accessing database <DBName> because snapshot isolation is not allowed in this database. Use ALTER DATABASE to allow snapshot isolation. For more information, provide tracing ID to customer support."

Resolution:

It worked by Executing the command "ALTER DATABASE [DB name] SET ALLOW_SNAPSHOT_ISOLATION ON" on the hub database.

You also had a predecessor script that reset the snapshot_isolation flag back to OFF. Upon fixing it, sync happened successfully.

Please do not forget to mark as accept answer.

It will be beneficial for other community members with the same issue.

Regards.,

Oury
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SQL Data Sync | Snapshot isolation transaction failed accessing database '***' because snapshot isolation is not allowed in this database.

2 answers