Perl script that reports SQL Server AD accounts which are now longer valid by verifying the output of sp_validlogins system stored procedure against SID stored in AD. This is done to ensure only accounts that do not exist are reported since sp_validlogins will only check the name and not SID against AD. Accounts that are renamed will retain the same SID, resulting in false positives.
When doing bulk data changes it may be beneficial to disable indexes prior to starting the operation. Fortunately, SQL's rich metadata makes this very easy to automate in a robust fashion.