Getting better performance when searching for accounts

Question

I'm trying to find an efficient way to query large amounts of user accounts in ActiveDirectory, and I'm having a bit of an issue. I have a script that goes through a file exported from another employee management program grabbing employeeIDs, which I then search for in ActiveDirectory. Every user account has an associated employeeID, and I use whether or not a certain ID is found in A/D to show whether an account should be created or deleted (if in file but not A/D, create; if in A/D but not file, delete). My problem is that I cannot find an efficient way to do this. My old method was to search for every employeeID one at a time with Get-ADUser, but this was very slow. I've also tried pulling down all the non-system accounts, and then using Where-Object on the list to filter out the account that matches. This also gets very slow with large amounts of accounts because Where-Object is checking every single account in my array of accounts. I think there must be a faster way to do this, s…

Accepted Answer

I'd start by doing one bulk query of AD, and building a hash table (Key = EmployeeID, Value = DN), and then work from that.

```
$hash = @{}

Get-ADUser -Properties EmployeeID -Filter * |
 foreach {$hash[$_.EmployeeID] = $_.DistinguishedName}

$csv = Import-CSV -Path $someFile
 Foreach($line in $csv){
  $DoesAccountExist = [bool]($hash[$line.employeeid])
}
```

$hash[$line.employeeid] will return the DN of the user that belongs to that employeeid if it's in the table.

Getting better performance when searching for accounts

Solution

Problem