The importance of preventing deadlocks in an SQL Server

Of all the topics relating to SQL Server monitoring and maintenance, deadlocks should arguably receive the most attention because of the issues they can cause and the benefits that come from troubleshooting them.

Experienced DBAs will already know all about deadlocking in SQL Server environments, but for the uninitiated here is a run-through of what they are and why they should be addressed rather than left to linger.

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Deadlocking leads to failed processes

One of the main reasons to find all SQL deadlocks and make sure your server is free of them going forward is that when they occur, they invariably result in processes being terminated.

The reason for this is that deadlocks are, by definition, conflicts between processes over resources which cannot be resolved without one of the competing processes being selected as the victim and thus put out to pasture.

From the point of view of maintaining data integrity across an SQL Server instance, deadlocking is obviously a vital aspect of the normal running of the database. However, if deadlocks keep occurring then processes will continue to fail, and this is clearly suboptimal.

App crashes could become common

The knock-on effect of deadlocks which cause processes to fail is that the apps which initiated them in the first place could end up grinding to a halt, which will obviously be noticeable to end-users and will limit the efficiency and effectiveness of the software you have built to harness your database in the first place.

Of course, you can account for deadlocks in the design of apps so that when they do arise, they are not the root cause of a crash but are rather encompassed and overcome automatically to create a smoother experience. Even so, it is still better to stop deadlocks from emerging in the first place, which is why it is important to initiate preventative measures rather than just patching problems after the fact.

Performance can always be improved

Dealing with deadlocks in SQL Server is necessary as part of your broader efforts to ensure that performance is at its peak as frequently as possible.

You might see deadlocks in the same way as you view standard blocking in a database. However, while blocks are equally important in terms of data integrity, they are also not as directly indicative of a fault that needs to be fixed and does not cause processes to fail in the same way.

By staying on the lookout for deadlocks, you will be able to preserve and even improve server performance and avoid one of the most common pitfalls of database administration.

Tools will help clear up deadlocks

You need not go it alone in the war against SQL deadlocks, since with modern monitoring tools it has never been easier to get alerted when they occur and also be equipped with the knowledge and features you need to remedy persistent deadlocking.

The more time you spend with SQL Server, the better you will get at managing deadlocks, so the main takeaway is that a proactive approach to troubleshooting should be at the top of the agenda, along with learning the ropes through the right course.