functions/Test-DbaOptimizeForAdHoc.ps1

function Test-DbaOptimizeForAdHoc {
    <#
        .SYNOPSIS
            Displays information relating to SQL Server Optimize for AdHoc Workloads setting. Works on SQL Server 2008-2016.
 
        .DESCRIPTION
            When this option is set, plan cache size is further reduced for single-use ad hoc OLTP workload.
 
            More info: https://msdn.microsoft.com/en-us/library/cc645587.aspx
            http://www.sqlservercentral.com/blogs/glennberry/2011/02/25/some-suggested-sql-server-2008-r2-instance-configuration-settings/
 
            These are just general recommendations for SQL Server and are a good starting point for setting the "optimize for adhoc workloads" option.
 
        .PARAMETER SqlInstance
            A collection of one or more SQL Server instance names to query.
 
        .PARAMETER SqlCredential
            Login to the target instance using alternative credentials. Windows and SQL Authentication supported. Accepts credential objects (Get-Credential)
 
    .PARAMETER EnableException
            By default, when something goes wrong we try to catch it, interpret it and give you a friendly warning message. This avoids overwhelming you with "sea of red" exceptions, but is inconvenient because it basically disables advanced scripting. Using this switch turns this "nice by default" feature off and enables you to catch exceptions with your own try/catch.
 
        .NOTES
            Tags: Configure, SPConfigure
            Author: Brandon Abshire, netnerds.net
 
            Website: https://dbatools.io
            Copyright: (C) Chrissy LeMaire, clemaire@gmail.com
            License: MIT https://opensource.org/licenses/MIT
 
        .LINK
            https://dbatools.io/Test-DbaOptimizeForAdHoc
 
        .EXAMPLE
            Test-DbaOptimizeForAdHoc -SqlInstance sql2008, sqlserver2012
 
            Validates whether Optimize for AdHoc Workloads setting is enabled for servers sql2008 and sqlserver2012.
    #>

    [CmdletBinding()]
    param (
        [parameter(Position = 0, Mandatory = $true, ValueFromPipeline = $True)]
        [Alias("ServerInstance", "SqlServer", "SqlServers")]
        [DbaInstance[]]$SqlInstance,
        [PSCredential]$SqlCredential,
        [Alias('Silent')]
        [switch]$EnableException
    )

    begin {
        $notesAdHocZero = "Recommended configuration is 1 (enabled)."
        $notesAsRecommended = "Configuration is already set as recommended."
        $recommendedValue = 1
    }
    process {

        foreach ($instance in $SqlInstance) {
            try {
                Write-Message -Level Verbose -Message "Connecting to $instance."
                $server = Connect-SqlInstance -SqlInstance $instance -SqlCredential $sqlcredential -MinimumVersion 10
            }
            catch {
                Stop-Function -Message "Failure" -Category ConnectionError -ErrorRecord $_ -Target $instance -Continue
            }

            #Get current configured value
            $optimizeAdHoc = $server.Configuration.OptimizeAdhocWorkloads.ConfigValue

            #Setting notes for optimize adhoc value
            if ($optimizeAdHoc -eq $recommendedValue) {
                $notes = $notesAsRecommended
            }
            else {
                $notes = $notesAdHocZero
            }

            [pscustomobject]@{
                ComputerName             = $server.NetName
                InstanceName             = $server.ServiceName
                SqlInstance              = $server.DomainInstanceName
                CurrentOptimizeAdHoc     = $optimizeAdHoc
                RecommendedOptimizeAdHoc = $recommendedValue
                Notes                    = $notes
            }
        }
    }
}