When SQL Server slows down, it is not always easy to figure out why. That is where Wait Statistics come into play — they act like a performance stethoscope, helping DBAs listen to what SQL Server is waiting on. Every query, every process, leaves behind clues in the form of waits. By understanding these waits, you can diagnose bottlenecks, uncover hidden issues, and fine-tune your server for peak performance.
In this series, I will tell you some relevant concepts, show you how to read them, and help you decide what actions to take — so you are not just guessing anymore.
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12. April 2025
Mehedi
SQL Server
When it comes to query performance tuning in SQL Server, key lookups are often the silent culprits that slow things down. This seemingly small operation can become expensive when repeated over thousands—or millions—of rows. In this article, we will break down what a key lookup is, why it happens, and how you can eliminate it with smarter indexing strategies. By addressing key lookups, you can significantly reduce I/O and boost query speed. So grab your execution plan and let’s uncover the hidden costs!
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