In the previous article in this series, I showed you how to use the Active Directory Users and Computers console to create and manage user accounts. In this article, I want to continue the discussion by teaching you about groups.

In a domain environment, user accounts are essential. A user account gives a user a unique identity on the network. This means that it is possible to track the user’s online activity. It is also possible to give a user account a unique set of permissions, assign the user a unique e-mail address, and meet all of the user’s other individual needs.

In the previous part of this article series, we began discussing the Active Directory Users and Computers console. Although that article explained how to connect to the domain of choice using the console, it never actually explained how to use the console for day-to-day management tasks. In this article, we will show you some basic techniques for user account maintenance.

The row_number function is an extremely powerful tool that I use to simplify and optimize solutions to many
problems. Occasionally I needed to calculate nondeterministic row numbers where order didn’t matter. For
example, suppose you have the following t1 table:

You need to return all rows from t1 along with unique incrementing row numbers in no particular order. If
order doesn’t matter, of course you can always specify an existing column from the table in the row_number
function’s order by clause:

from dbo.t1;

However, the execution plan for the query would involve sorting (or an index order scan if an index exists on
the sort column). Here’s the plan you get for the above query:

If the order of the row numbers doesn’t matter to you, you’d probably rather not pay the sort penalty. The
problem is that SQL Server doesn’t allow a constant in the row_number function’s order by clause. Try running
the following query:

And you will get the following error:

Until recently, in order to avoid sorting I defined a table expression (CTE or derived table) based on a query
that returns the table rows along with a constant (call it const). In the outer query I invoked the row_number
function with order by const:

from c;

Here, the optimizer is smart enough to realize that sorting is not required. Here’s the plan I got for this query
(notice there’s no sort operation):

Even though this technique avoids sorting, it is a bit awkward. Recently I got a tip from a T. Wong how to
achieve the same thing without the need for a table expression—simply specify order by (select 0)!

Here’s the solution query with the new technique:

from dbo.t1;

It is much more elegant than the previous technique, and also here the plan shows that the optimizer realized
that sorting is not needed:

                      |--Table Scan(OBJECT:([tempdb].[dbo].[t1]))

On April 13, Microsoft released an update for Microsoft Office Outlook 2007 that addresses performance problems with large mailboxes. The Microsoft article "Description of the update for Outlook 2007: April 13, 2007" describes what the patch fixes. I regularly use three different Outlook 2007 profiles against three different Exchange Server organizations, and I've occasionally noticed poor performance on one particular server. I eagerly installed the patch and found that, as promised, it helped improve the performance of Outlook 2007 on that server. However, I decided to experiment a bit and found an even more dramatic improvement from doing something that I'd never done before: I turned off Cached Exchange Mode.