functions/Invoke-DBSafeShrink.ps1
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function Invoke-DBSafeShrink { <# .SYNOPSIS Shrinks a Sql Server mdf database file without fragmenting the indexes. .DESCRIPTION Shrinks a Sql Server mdf database file without fragmenting the indexes. Can be used to migrate indexes to a new filegroup, or just shrink and move the indexes back to the original filegroup after the shrink is done. Typically runs faster than a normal shrink operation. IMPORTANT: The second file that gets created will match the used size of the original filegroup. You must have enough disk space to support this. Wrote this after I read this post by Paul Randal: https://www.sqlskills.com/blogs/paul/why-you-should-not-shrink-your-data-files/ I always knew shrinking was very bad, but until I read these comments by Paul my brain never clicked that there could be a better way: QUOTE (Paul Randal): The method I like to recommend is as follows: - Create a new filegroup - Move all affected tables and indexes into the new filegroup using the CREATE INDEX … WITH (DROP_EXISTING = ON) ON syntax, to move the tables and remove fragmentation from them at the same time - Drop the old filegroup that you were going to shrink anyway (or shrink it way down if its the primary filegroup) - Move the indexes back to the original filegroup if desired This script automates those steps so you don't have to. .PARAMETER ServerInstance The sql server instance to connect to. .PARAMETER Databases The databases to shrink. A string array. .PARAMETER Credentials Specifies credentials to connect to the database with. If not supplied then a trusted connection will be used. .PARAMETER FileGroupName The file group name to shrink. Defaults to PRIMARY. It does not matter if there are multiple mdf or ldf files assigned. .PARAMETER NewFileDirectory If passed, then this will be the directory that the new temporary file will be created in. Otherwise it will default to the same directory as the primary file. This directory will be created if it does not exist. If it already exists, then nothing happens. If the path is a local path, then the directory will be created on the server using xp_create_sub directory. NOTES: - The drive must exist, else an exception will occur - The SQL Server account must have write access to the target folder, else an exception will occur .PARAMETER Direction If the direction is twoway then the the indexes are moved to the temporary file and back after the original file is shrunk. If the direction is oneway, then the indexes are moved to the temporary file, and the process will be complete. .PARAMETER AdjustRecovery If this switch is enabled then the recovery model of the database will be temporarily changed to SIMPLE, then put back to the original recovery model. If the switch is missing, then the recovery model will not be changed. .PARAMETER ShrinkTimeout If the original requires shrinking in a twoway operation, then the shrinks will occur in very small chunks at a time. This timeout will control how long that operation can run before timing out. NOTES: This timeout is in minutes. .PARAMETER ShrinkIncrementMB The amount of MB to shrink the file each shrink attempt. If left as the default of 0 then a simple formula will adjust the shrink increment based upon the file size. .PARAMETER IndexMoveTimeout The amount of time that controls how long a index move can run before timing out. NOTES: This timeout is in minutes. .PARAMETER MinimumFreeSpaceMB The file shrunk must have at least this amount of free space, otherwise the shrink operation will write out a warning and skip the shrink operation for this file. .PARAMETER TlogBackupJobName The name of a TLOG back up job name. If passed in, then the job will be temporarily disabled until the process finishes as TLOG backups will interfere with the file operations. .INPUTS None. You cannot pipe objects to this script. .OUTPUTS Generates a table of records detailing before and after sizes for each filegroup shrunk. .EXAMPLE PS> .\Invoke-DBSafeShrink -ServerInstance "servername" -Databases "AdventureWorks2008","AdventureWorks2012" .EXAMPLE PS> .\Invoke-DBSafeShrink -ServerInstance "servername" -Databases "AdventureWorks2008","AdventureWorks2012" -UserName "user.name" -Password "ilovelamp" .EXAMPLE PS> .\Invoke-DBSafeShrink -ServerInstance "servername" -Databases "AdventureWorks2008","AdventureWorks2012" -MinimumFreeSpaceMB 1 -NewFileDirectory "D:\sqltemp\" .LINK https://github.com/tcartwright/tcdbtools .NOTES Author: Tim Cartwright #> [CmdletBinding()] param ( [Parameter(Mandatory=$true)] [string]$ServerInstance, [Parameter(Mandatory=$true)] [string[]]$Databases, [pscredential]$Credentials, [string]$FileGroupName = "PRIMARY", [System.IO.DirectoryInfo]$NewFileDirectory, [ValidateSet("oneway", "twoway")] [string]$Direction = "twoway", [switch]$AdjustRecovery, [ValidateRange(1, 20)] [int]$ShrinkTimeout = 10, [ValidateRange(0, 20000)] [int]$ShrinkIncrementMB = 0, [ValidateRange(1, 20)] [int]$IndexMoveTimeout = 5, [int]$MinimumFreeSpaceMB = 250, [string]$TlogBackupJobName ) begin { $sqlCon = InitSqlObjects -ServerInstance $ServerInstance -Credentials $Credentials $SqlCmdArguments = $sqlCon.SqlCmdArguments $server = $sqlCon.server $shrinkTimeOut = ([Timespan]::FromMinutes($ShrinkTimeout).TotalSeconds) $IndexMoveTimeout = ([Timespan]::FromMinutes($IndexMoveTimeout).TotalSeconds) <# # IF THEY PASSED IN A NEW DIRECTORY, MAKE SURE IT IS CREATED #> if ($NewFileDirectory) { if (([Uri]$NewFileDirectory.FullName).IsUnc) { if (-not $NewFileDirectory.Exists) { New-Item $NewFileDirectory.FullName -ItemType Directory -Force | Out-Null } } else { try { # create the directory on the sql server if it does not exist. has no effect if the directory is already created. Throws an exception if the path is invalid, usually the directory $sql = "EXECUTE master.dbo.xp_create_subdir '$($NewFileDirectory.FullName)'" Write-Verbose $sql Invoke-Sqlcmd @SqlCmdArguments -query $sql } catch { throw exit 1 } } } <# # IF THEY PASSED IN A TLOG BACKUP JOB NAME THEN STOP IT, AND WAIT A BIT FOR IT TO FINISH #> if ($TlogBackupJobName) { # lets disable the job. We must ensure to re-enable it at the end $sql = "EXEC msdb.dbo.sp_update_job @job_name = N'$TlogBackupJobName', @enabled = 0 ;" Write-Verbose $sql Invoke-Sqlcmd @SqlCmdArguments -query $sql # now, lets wait a bit so that if the job is running we can let it finish up $sql = "DECLARE @sanityCounter INT = 0 WHILE EXISTS ( SELECT [job].[name] ,job.job_id ,[job].[originating_server] ,[activity].[run_requested_date] ,DATEDIFF(SECOND, [activity].[run_requested_date], GETDATE()) AS elapsed FROM msdb.dbo.sysjobs_view AS job JOIN msdb.dbo.sysjobactivity AS activity ON job.job_id = activity.job_id JOIN msdb.dbo.syssessions AS sess ON sess.session_id = activity.session_id JOIN ( SELECT MAX(agent_start_date) AS max_agent_start_date FROM msdb.dbo.syssessions ) AS sess_max ON [sess].[agent_start_date] = [sess_max].[max_agent_start_date] WHERE [activity].[run_requested_date] IS NOT NULL AND [activity].[stop_execution_date] IS NULL AND [job].[name] = '$TlogBackupJobName') BEGIN -- wait at max 2 minutes SET @sanityCounter += 1 IF @sanityCounter > 24 BREAK WAITFOR DELAY '00:00:05' END" Write-Verbose $sql Invoke-Sqlcmd @SqlCmdArguments -query $sql } $sw = [System.Diagnostics.Stopwatch]::StartNew() $swFormat = "hh\:mm\:ss" $ret = @{} Write-InformationColored "[$($sw.Elapsed.ToString($swFormat))] STARTING" -ForegroundColor Yellow foreach($Database in $Databases) { $SqlCmdArguments.Database = $Database $db = $server.Databases[$Database] if ($db.Name -ne $Database) { Write-Warning "Can't find the database [$Database] in '$ServerInstance'" continue }; <# # ADJUST THE RECOVERY IF REQUESTED, IF WE ARE ALREADY NOT IN SIMPLE #> if ($AdjustRecovery.IsPresent -and $originalRecovery -ine "Simple") { Write-Information "[$($sw.Elapsed.ToString($swFormat))] SETTING DATABASE RECOVERY TO SIMPLE" $sql = "ALTER DATABASE [$Database] SET RECOVERY SIMPLE" Write-Verbose $sql Invoke-Sqlcmd @SqlCmdArguments -Query "$sql" } } } process { foreach($Database in $Databases) { $SqlCmdArguments.Database = $Database $db = $server.Databases[$Database] if ($db.Name -ne $Database) { Write-Warning "Can't find the database [$Database] in '$ServerInstance'" continue }; $originalFG = $db.FileGroups | Where-Object { $_.Name -ieq $fileGroupName } | Select-Object -First 1 if (-not $originalFG) { Write-Warning "Filegroup [$fileGroupName] not found in database: [$Database]" continue } $freeSpace = GetFreeSpace -SqlCmdArguments $SqlCmdArguments -Database $Database -FileGroupName $FileGroupName | Where-Object { $_.used_space_mb -gt 0 } $totals = $freeSpace | Measure-Object -Property free_space_mb, used_space_mb -Sum if ($totals[0].Sum -lt $MinimumFreeSpaceMB ) { Write-Warning "Database [$Database] does not have any files with the minimum required free space of $MinimumFreeSpaceMB MB for this operation to continue." continue } $usedTotalSize = $totals[1].Sum # in case of a restart, figure out the average without counting the shrink temp file in the divisor $averageUsedSize = $totals[1].Sum / ([System.Object[]]($freespace | Where-Object { $_.filegroup_name -ine "SHRINK_DATA_TEMP" })).Count $originalRecovery = $db.RecoveryModel foreach ($fs in $freeSpace) { $fileInfo = [PSCustomObject] @{ Database = $Database FileGroupName = [string]$fs.filegroup_name FileName = [string]$fs.file_name SizeBefore = [int]$fs.current_size_mb UsedBefore = [int]$fs.used_space_mb FreeBefore = [int]$fs.free_space_mb SizeAfter = [int]0 UsedAfter = [int]0 FreeAfter = [int]0 } $ret.Add("$Database-$($fileInfo.FileName)", $fileInfo) | Out-Null } $originalFile = $originalFG.Files | Where-Object { $_.IsPrimaryFile } | Select-Object -First 1 # capture this before moving any indexes as the values will be different after $originalFiles = $originalFG.Files | ForEach-Object { [PSCustomObject] @{ Database = $Database Name = [string]$_.Name Size = $ret["$Database-$($_.Name)"].SizeBefore } } $fi = [System.IO.FileInfo]$originalFile.FileName $newFileName = "$($fi.DirectoryName)\$($fi.BaseName)_SHRINK_DATA_TEMP$($fi.Extension)" if ($NewFileDirectory) { $newFileName = [System.IO.Path]::Combine($NewFileDirectory.FullName, ([System.IO.FileInfo]$newFileName).Name) } Write-InformationColored "[$($sw.Elapsed.ToString($swFormat))] SHRINKING SERVER: $ServerInstance, DATABASE: $Database, FILEGROUP: $fileGroupName`r`n" -ForegroundColor Cyan <# # SETUP THE NEW FILEGROUP AND FILE, BACKUP OPERATIONS CAN CONFLICT, ITS BEST TO STOP BACK JOBS AHEAD OF TIME UNLESS IT ALREADY EXISTS #> Write-Information "[$($sw.Elapsed.ToString($swFormat))] CREATING FG SHRINK_DATA_TEMP" $sql = " IF NOT EXISTS (SELECT 1 FROM [$Database].sys.[filegroups] AS [f] WHERE [f].[name] = 'SHRINK_DATA_TEMP') BEGIN ALTER DATABASE [$Database] ADD FILEGROUP SHRINK_DATA_TEMP END IF NOT EXISTS (SELECT 1 FROM [$Database].sys.[database_files] AS [df] WHERE [df].[name] = 'SHRINK_DATA_TEMP') BEGIN ALTER DATABASE [$Database] ADD FILE ( NAME = 'SHRINK_DATA_TEMP', FILENAME = '$newFileName', SIZE = $($usedTotalSize)MB, FILEGROWTH = $($originalFile.Growth)$($originalFile.GrowthType) ) TO FILEGROUP SHRINK_DATA_TEMP END DBCC SHRINKFILE([SHRINK_DATA_TEMP], TRUNCATEONLY) WITH NO_INFOMSGS; " try { PeformFileOperation -SqlCmdArguments $SqlCmdArguments -sql "$sql" } catch { Write-Warning $_.Exception.Message continue } <# # MOVE THE INDEXES FROM THE BASE FILEGROUP TO THE TARGET TEMP FILEGROUP #> MoveIndexes -db $db -fromFG $fileGroupName -toFG "SHRINK_DATA_TEMP" -indicator "-->" -timeout $IndexMoveTimeout -SqlCmdArguments $SqlCmdArguments <# # MOVE THE INDEXES BACK TO THE ORIGINAL FILEGROUP IF THE DIRECTION IS TWOWAY, AND REMOVE THE TEMP FILEGROUP AND FILE #> if ($direction -ieq "twoway") { <# # SHRINK THE OLD FILE GROUP DOWN A SMALL AMOUNT AT A TIME UNTIL WE REACH THE SMALLEST SIZE #> Write-InformationColored "[$($sw.Elapsed.ToString($swFormat))] SHRINKING FILES IN FG $fileGroupName" -ForegroundColor Magenta foreach($file in $originalFiles) { # shrink each file a percentage at a time to keep from possibly timing out the shrink. cause even EMPTY files take a long time to shrink. WTF. $fileName = $file.Name [int]$size = $file.Size Write-Verbose "LOOPING SHRINKFILE" $size = ShrinkFile -SqlCmdArguments $SqlCmdArguments -size $size -fileName $fileName -targetSizeMB $averageUsedSize -timeout $ShrinkTimeout -ShrinkIncrementMB $ShrinkIncrementMB | Select-Object -Last 1 } Write-InformationColored "[$($sw.Elapsed.ToString($swFormat))] FINISHED SHRINKING FILES IN FG $fileGroupName" -ForegroundColor Magenta MoveIndexes -db $db -fromFG "SHRINK_DATA_TEMP" -toFG $fileGroupName -indicator "<--" -timeout $IndexMoveTimeout -SqlCmdArguments $SqlCmdArguments # there have been occasions when an error occurred saying the file was not empty, until an empty file was issued. even though all of the indexes had been moved back $sql = "DBCC SHRINKFILE(SHRINK_DATA_TEMP, 'EMPTYFILE') WITH NO_INFOMSGS;" Write-Verbose $sql Invoke-Sqlcmd @SqlCmdArguments -Query "$sql" -QueryTimeout $shrinkTimeOut Write-Information "[$($sw.Elapsed.ToString($swFormat))] REMOVING SHRINK_DATA_TEMP FG AND FILE" $sql = " IF EXISTS (SELECT 1 FROM [$($SqlCmdArguments.Database)].sys.[database_files] AS [df] WHERE [df].[name] = 'SHRINK_DATA_TEMP') BEGIN ALTER DATABASE [$($SqlCmdArguments.Database)] REMOVE FILE [SHRINK_DATA_TEMP] END IF EXISTS (SELECT 1 FROM [$($SqlCmdArguments.Database)].sys.[filegroups] AS [f] WHERE [f].[name] = 'SHRINK_DATA_TEMP') BEGIN ALTER DATABASE [$($SqlCmdArguments.Database)] REMOVE FILEGROUP [SHRINK_DATA_TEMP] END" PeformFileOperation -SqlCmdArguments $SqlCmdArguments -sql "$sql" } <# # PERFORM ONE LAST TRUNCATEONLY SHRINK #> Write-Information "[$($sw.Elapsed.ToString($swFormat))] SHRINKING FILES IN FG [$fileGroupName] WITH TRUNCATEONLY" foreach($file in $originalFiles) { $fileName = $file.Name $sql = "DBCC SHRINKFILE($fileName, TRUNCATEONLY) WITH NO_INFOMSGS" Write-Verbose "$sql" Invoke-Sqlcmd @SqlCmdArguments -Query $sql -QueryTimeout $shrinkTimeOut | Format-Table } <# # RECORD THE CHANGES AFTER THE OPERATION HAS COMPLETED FOR THE FILES #> $freeSpace = GetFreeSpace -SqlCmdArguments $SqlCmdArguments -Database $Database -FileGroupName $FileGroupName $freeSpace | ForEach-Object { $obj = $ret["$Database-$($_.file_name)"] if ($obj) { $obj.SizeAfter = [int]$_.current_size_mb $obj.UsedAfter = [int]$_.used_space_mb $obj.FreeAfter = [int]$_.free_space_mb } } Write-InformationColored "[$($sw.Elapsed.ToString($swFormat))] FISNISHED SHRINKING SERVER: $ServerInstance, DATABASE: $Database, FILEGROUP: $fileGroupName`r`n" -ForegroundColor Cyan } } end { foreach($Database in $Databases) { $SqlCmdArguments.Database = $Database $db = $server.Databases[$Database] if ($db.Name -ne $Database) { Write-Warning "Can't find the database [$Database] in '$ServerInstance'" continue }; <# # SET THE RECOVERY BACK TO THE ORIGINAL RECOVERY IF REQUESTED AND THE ORIGINAL WAS NOT SIMPLE #> if ($AdjustRecovery.IsPresent -and $originalRecovery -ine "Simple") { Write-Information "[$($sw.Elapsed.ToString($swFormat))] RESETTING DATABASE RECOVERY MODE TO '$($originalRecovery.ToString().ToUpper())'" $sql = "ALTER DATABASE [$Database] SET RECOVERY $originalRecovery" Write-Verbose $sql Invoke-Sqlcmd @SqlCmdArguments -Query $sql -QueryTimeout $shrinkTimeOut } } $sw.Stop() Write-InformationColored "[$($sw.Elapsed.ToString($swFormat))] FINISHED" -ForegroundColor Yellow if ($TlogBackupJobName) { $sql = "EXEC msdb.dbo.sp_update_job @job_name = N'$TlogBackupJobName', @enabled = 1 ;" Write-Verbose $sql Invoke-Sqlcmd @SqlCmdArguments -query $sql } return $ret.Values } } |