When optimizing your database server, you need to tune the performance of individual queries. This is as important as—perhaps even more important than—tuning other aspects of your server installation, that affect performance, such as hardware and software configurations.
Even if your database server runs on the most powerful hardware available, its performance can be negatively affected by a handful of misbehaving queries. In fact, even one bad query, sometimes called a "runaway query," can cause serious performance issues for your database.
Conversely, the overall performance of your database can be greatly improved by tuning a set of most expensive or most often executed queries. In this article, I will look at some of the techniques you can employ to identify and tune the most expensive and worst performing queries on your server.
* Analyzing execution plans
* Optimizing queries
* Estimated Cost of Execution
* Analyzing an Execution Plan
* The Covering Index
* Indexed Views
* Identifying Which Queries to Tune
* Customer Order Query Exercise
Tarpitting is the practice of deliberately inserting a delay into certain SMTP communications that are associated with spam or with other unwanted traffic. To be effective, these kinds of communications typically rely on generating a high volume of traffic. By slowing an SMTP conversation, you can dramatically reduce the rate at which automated spam can be sent or at which a dictionary attack can be conducted. Legitimate traffic may also be slowed by tar pitting.
The tar pit feature is available in Microsoft Windows Server 2003 and in several third-party SMTP servers. The tar pit feature in Windows Server 2003 works by slowing all responses that contain SMTP protocol 5.x.x error codes. An administrator can configure the delay that is introduced by the tar pit feature.
Tar pitting affects only anonymous SMTP connections. Authenticated sessions are exempt. Therefore, if you regularly exchange lots of SMTP mail with another organization,
and you find that tar pitting is affecting that traffic, you can bypass tar pitting for that organization by authenticating SMTP communications.