functions/Test-DbaVirtualLogFile.ps1

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function Test-DbaVirtualLogFile {
    <#
 .SYNOPSIS
  Returns database virtual log file information for database files on a SQL instance.
 
 .DESCRIPTION
  As you may already know, having a TLog file with too many VLFs can hurt database performance.
 
  Too many virtual log files can cause transaction log backups to slow down and can also slow down database recovery and, in extreme cases, even affect insert/update/delete performance.
 
   References:
   http://www.sqlskills.com/blogs/kimberly/transaction-log-vlfs-too-many-or-too-few/
   http://blogs.msdn.com/b/saponsqlserver/archive/2012/02/22/too-many-virtual-log-files-vlfs-can-cause-slow-database-recovery.aspx
 
  If you've got a high number of VLFs, you can use Expand-SqlTLogResponsibly to reduce the number.
 
 .PARAMETER SqlInstance
  SQLServer name or SMO object representing the SQL Server to connect to. This can be a collection and receive pipeline input.
 
 .PARAMETER SqlCredential
  PSCredential object to connect under. If not specified, current Windows login will be used.
 
 .PARAMETER Database
  The database(s) to process - this list is auto-populated from the server. If unspecified, all databases will be processed.
 
 .PARAMETER ExcludeDatabase
  The database(s) to exclude - this list is auto-populated from the server
 
 .PARAMETER IncludeSystemDBs
  Switch parameter that when used will display system database information
 
 .PARAMETER Detailed
  Returns all information provided by DBCC LOGINFO plus the server name and database name
 
 .NOTES
  Tags: DisasterRecovery, Backup
 
  Website: https://dbatools.io
  Copyright: (C) Chrissy LeMaire, clemaire@gmail.com
  License: GNU GPL v3 https://opensource.org/licenses/GPL-3.0
 
 .LINK
  https://dbatools.io/Test-DbaVirtualLogFile
 
 .EXAMPLE
  Test-DbaVirtualLogFile -SqlInstance sqlcluster
 
  Returns all user database virtual log file counts for the sqlcluster instance
 
 .EXAMPLE
  Test-DbaVirtualLogFile -SqlInstance sqlserver | Where-Object {$_.Count -ge 50}
 
  Returns user databases that have more than or equal to 50 VLFs
 
 .EXAMPLE
  @('sqlserver','sqlcluster') | Test-DbaVirtualLogFile
 
  Returns all VLF information for the sqlserver and sqlcluster SQL Server instances. Processes data via the pipeline.
 
 .EXAMPLE
  Test-DbaVirtualLogFile -SqlInstance sqlcluster -Database db1, db2
 
  Returns VLF counts for the db1 and db2 databases on sqlcluster.
 #>

    [CmdletBinding()]
    [OutputType([System.Collections.ArrayList])]
    param ([parameter(ValueFromPipeline, Mandatory = $true)]
        [Alias("ServerInstance", "SqlServer")]
        [DbaInstanceParameter[]]$SqlInstance,
        [PSCredential]$SqlCredential,
        [Alias("Databases")]
        [object[]]$Database,
        [object[]]$ExcludeDatabase,
        [switch]$IncludeSystemDBs,
        [switch]$Detailed
    )

    PROCESS {
        foreach ($servername in $SqlInstance) {
            Write-Verbose "Connecting to $servername"
            try {
                $server = Connect-SqlInstance $servername -SqlCredential $SqlCredential
            }
            catch {
                Write-Warning "Can't connect to $instance, skipping..."
                Continue
            }

            $dbs = $server.Databases
            #If IncludeSystemDBs is true, include systemdbs
            #only look at online databases (Status equal normal)

            if ($Database) {
                $dbs = $dbs | Where-Object { $Database -contains $_.Name }
            }
            if ($ExcludeDatabase) {
                $dbs = $dbs | Where-Object Name -notin $ExcludeDatabase
            }

            if ($IncludeSystemDBs) {
                $dbs = $dbs | Where-Object { $_.status -eq 'Normal' }
            }
            else {
                $dbs = $dbs | Where-Object { $_.status -eq 'Normal' -and $_.IsSystemObject -eq 0 }
            }

            foreach ($db in $dbs) {
                try {
                    Write-Verbose "Querying $($db.name) on $servername."
                    #Execute query against individual database and add to output

                    if ($Detailed -eq $true) {
                        $table = New-Object System.Data.Datatable
                        $servercolumn = $table.Columns.Add("Server")
                        $servercolumn.DefaultValue = $server.name
                        $dbcolumn = $table.Columns.Add("Database")
                        $dbcolumn.DefaultValue = $db.name

                        $temptable = $db.ExecuteWithResults("DBCC LOGINFO").Tables

                        foreach ($column in $temptable.Columns) {
                            $null = $table.Columns.Add($column.ColumnName)
                        }

                        foreach ($row in $temptable.rows) {
                            $table.ImportRow($row)
                        }
                        
                        $table
                    }
                    else {
                        [PSCustomObject]@{
                            Server   = $server.name
                            Database = $db.name
                            Count    = $db.ExecuteWithResults("DBCC LOGINFO").Tables.Rows.Count
                        }
                    }
                }
                catch {
                    Write-Exception $_
                    Write-Warning "Unable to query $($db.name) on $servername"
                    continue
                }
            }
        }
    }
}