Use-DbRetry.ps1
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<#
.SYNOPSIS Retry SQL operations. .DESCRIPTION Retry SQL operations. These are only in limited scenarios: * SQL Server deadlocks and timeouts. * SQL Server policy evaluation errors (caused by race conditions). .PARAMETER ScriptBlock The script you want to execute. It's best to keep this as short as possible, and don't modify variables outside of the scriptblock's scope as they may not be preserved. .PARAMETER Tries The maximum number of tries to attempt. This defaults to 3, meaning one attempt plus two retries may be made. .INPUTS A scriptblock. .OUTPUTS Anything output by the scriptblock. But failure information is also written to the Verbose stream. .EXAMPLE $serverInstance = ".\SQL2016" New-DbConnection $serverInstance master | New-DbCommand "If Object_Id('dbo.Moo', 'U') Is Not Null Drop Table dbo.Moo; Create Table dbo.Moo (A Int Identity (1, 1) Primary Key, B Nvarchar(Max));" | Get-DbData $dbData = New-DbConnection $serverInstance master | New-DbCommand "Select * From dbo.Moo" | Enter-DbTransaction -PassThru | Get-DbData -As DataTables $dbData.Alter(@{ A = 1; B = "B" }) try { $dbData2 = New-DbConnection $serverInstance master | New-DbCommand "Select * From dbo.Moo" -CommandTimeout 2 | ForEach { Use-DbRetry { Get-DbData $_ } -Verbose } } catch { "Exception was caught: $_" } Exit-DbTransaction $dbData -Rollback This drops and recreates a dbo.Moo table (no output), begins a transaction and then upserts a record (returning 1 for 1 record modified). It then starts a second connection with a short timeout and attempts to select data from the table again. With verbose output this shows a series of timeouts and retry attempts, before throwing an exception which we catch (outputs exception text). The transaction is then rolled back (no output). #> function Use-DbRetry { [CmdletBinding()] param ( [Parameter(Mandatory = $true)] [scriptblock] $Script, [int] $Tries = 3 ) $try = 1 while ($try -le $Tries) { try { $ErrorActionPreference = "Stop" . $Script break } catch { if (Test-Error -Type System.Data.SqlClient.SqlException) { if (Test-Error @{ Number = 1205 }) { Write-Verbose "Caught SQL deadlock. Try $try." $try++ } elseif (Test-Error @{ Number = -2 }) { Write-Verbose "Caught SQL timeout. Try $try." $try++ } else { Write-Verbose "Caught unknown SQL error: $_" throw } } elseif (Test-Error Microsoft.SqlServer.Management.Dmf.PolicyEvaluationException) { Write-Verbose "Caught SQL policy evaluation error. Retry $try." $try++ } else { Write-Verbose "Caught unknown non-SQL error: $_" throw } if ($try -gt $Tries) { throw } else { Start-Sleep -Milliseconds (Get-Random 5000) # Somewhere up to 5 seconds } } } } |