functions/Get-DbaLastGoodCheckDb.ps1

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Function Get-DbaLastGoodCheckDb {
<#
.SYNOPSIS
Get date/time for last known good DBCC CHECKDB
 
.DESCRIPTION
Retrieves and compares the date/time for the last known good DBCC CHECKDB, as well as the creation date/time for the database.
 
This function supports SQL Server 2005+
 
Please note that this script uses the DBCC DBINFO() WITH TABLERESULTS. DBCC DBINFO has several known weak points, such as:
 - DBCC DBINFO is an undocumented feature/command.
 - The LastKnowGood timestamp is updated when a DBCC CHECKFILEGROUP is performed.
 - The LastKnowGood timestamp is updated when a DBCC CHECKDB WITH PHYSICAL_ONLY is performed.
 - The LastKnowGood timestamp does not get updated when a database in READ_ONLY.
 
An empty ($null) LastGoodCheckDb result indicates that a good DBCC CHECKDB has never been performed.
 
SQL Server 2008R2 has a "bug" that causes each databases to possess two dbi_dbccLastKnownGood fields, instead of the normal one.
This script will only displaythis function to only display the newest timestamp. If -Verbose is specified, the function will announce every time more than one dbi_dbccLastKnownGood fields is encountered.
 
.PARAMETER SqlInstance
The SQL Server that you're connecting to.
 
.PARAMETER SqlCredential
Credential object used to connect to the SQL Server as a different user
 
.PARAMETER Databases
Return information for only specific databases
 
.PARAMETER Exclude
Return information for all but these specific databases
  
.PARAMETER Silent
Use this switch to disable any kind of verbose messages
 
.NOTES
Copyright (C) 2016 Jakob Bindslet (jakob@bindslet.dk)
 
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
 
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 
You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.
 
.LINK
DBCC CHECKDB:
 https://msdn.microsoft.com/en-us/library/ms176064.aspx
 http://www.sqlcopilot.com/dbcc-checkdb.html
Data Purity:
 http://www.sqlskills.com/blogs/paul/checkdb-from-every-angle-how-to-tell-if-data-purity-checks-will-be-run/
 https://www.mssqltips.com/sqlservertip/1988/ensure-sql-server-data-purity-checks-are-performed/
 
.EXAMPLE
Get-DbaLastGoodCheckDb -SqlInstance ServerA\sql987
 
Returns a custom object displaying Server, Database, DatabaseCreated, LastGoodCheckDb, DaysSinceDbCreated, DaysSinceLastGoodCheckDb, Status and DataPurityEnabled
 
.EXAMPLE
Get-DbaLastGoodCheckDb -SqlInstance ServerA\sql987 -SqlCredential (Get-Credential sqladmin) | Format-Table -AutoSize
 
Returns a formatted table displaying Server, Database, DatabaseCreated, LastGoodCheckDb, DaysSinceDbCreated, DaysSinceLastGoodCheckDb, Status and DataPurityEnabled.
Authenticates with SQL Server using alternative credentials.
 
#>

    [CmdletBinding()]
    Param (
        [parameter(Mandatory = $true, ValueFromPipeline = $true)]
        [Alias("ServerInstance", "SqlServer")]
        [object[]]$SqlInstance,
        [Alias("Credential")]
        [PsCredential]$SqlCredential,
        [switch]$Silent
    )
    
    DynamicParam {
        if ($SqlInstance) {
            return Get-ParamSqlDatabases -SqlServer $SqlInstance[0] -SqlCredential $SqlCredential
        }
    }
    
    begin {
        # Convert from RuntimeDefinedParameter object to regular array
        $databases = $psboundparameters.Databases
        $exclude = $psboundparameters.Exclude
    }
    
    process {
        foreach ($instance in $SqlInstance) {
            try {
                Write-Message -Level Verbose -Message "Connecting to $instance"
                $server = Connect-SqlServer -SqlServer $instance -SqlCredential $sqlcredential
            }
            catch {
                Stop-Function -Message "Failed to connect to: $instance" -Continue -Target $instance
            }
            
            if ($server.versionMajor -lt 9) {
                Stop-Function -Message "Get-DbaLastGoodCheckDb is only supported on SQL Server 2005 and above. Skipping Instance." -Continue -Target $instance
            }
            
            $dbs = $server.Databases
            
            if ($databases.count -gt 0) {
                $dbs = $dbs | Where-Object { $databases -contains $_.Name }
            }
            
            if ($exclude.count -gt 0) {
                $dbs = $dbs | Where-Object { $exclude -notcontains $_.Name }
            }
            
            # $dbs = $dbs | Where-Object {$_.IsAccessible}
            
            foreach ($db in $dbs) {
                Write-Message -Level Verbose -Message "Processing $($db.name) on $instances"
                
                if ($db.IsAccessible -eq $false) {
                    Stop-Function "The database $($db.name) is not accessible. Skipping database." -Continue -Target $db
                }
                
                $sql = "DBCC DBINFO ([$($db.name)]) WITH TABLERESULTS"
                Write-Message -Level Debug -Message "T-SQL: $sql"
                
                $resultTable = $db.ExecuteWithResults($sql).Tables[0]
                [datetime[]]$lastKnownGoodArray = $resultTable | Where-Object Field -eq 'dbi_dbccLastKnownGood' | Select-Object -ExpandProperty Value
                
                ## look for databases with two or more occurrences of the field dbi_dbccLastKnownGood
                if ($lastKnownGoodArray.count -ge 2) {
                    Write-Message -Level Verbose -Message "The database $($db.name) has $($lastKnownGoodArray.count) dbi_dbccLastKnownGood fields. This script will only use the newest!"
                }
                [datetime]$lastKnownGood = $lastKnownGoodArray | Sort-Object -Descending | Select-Object -First 1
                
                [int]$createVersion = ($resultTable | Where-Object Field -eq 'dbi_createVersion').Value
                [int]$dbccFlags = ($resultTable | Where-Object Field -eq 'dbi_dbccFlags').Value
                
                if (($createVersion -lt 611) -and ($dbccFlags -eq 0)) {
                    $dataPurityEnabled = $false
                }
                else {
                    $dataPurityEnabled = $true
                }
                
                $daysSinceCheckDb = (New-TimeSpan -Start $lastKnownGood -End (Get-Date)).Days
                $daysSinceDbCreated = (New-TimeSpan -Start $db.createDate -End (Get-Date)).Days
                
                if ($daysSinceCheckDb -lt 7) {
                    $Status = 'Ok'
                }
                elseif ($daysSinceDbCreated -lt 7) {
                    $Status = 'New database, not checked yet'
                }
                else {
                    $Status = 'CheckDB should be performed'
                }
                
                if ($lastKnownGood -eq '1/1/1900 12:00:00 AM') { Remove-Variable -Name lastKnownGood, daysSinceCheckDb }
                
                [PSCustomObject]@{
                    ComputerName = $server.NetName
                    InstanceName = $server.ServiceName
                    SqlInstance = $server.DomainInstanceName
                    Database = $db.name
                    DatabaseCreated = $db.createDate
                    LastGoodCheckDb = $lastKnownGood
                    DaysSinceDbCreated = $daysSinceDbCreated
                    DaysSinceLastGoodCheckDb = $daysSinceCheckDb
                    Status = $status
                    DataPurityEnabled = $dataPurityEnabled
                    CreateVersion = $createVersion
                    DbccFlags = $dbccFlags
                }
            }
        }
    }
}