Profiler, SQL Server's built-in tracing feature, is an invaluable tool for performance tuning and debugging SQL Server applications. With it, you can trace every request a database application makes to SQL Server and use that data to improve performance. For example, if you run a Profiler trace during a long-running process, you might find that SQL Server is using a table scan, encountering table locks, or running into other performance-robbing events. In most cases, I run Profiler at the request of a developer who's trying to debug some tricky database code. Occasionally, if time permits, I go on a preemptive strike and run my favorite trace, the duration trace. This Profiler trace looks for processes accessing SQL Server that take more than 1 second. One second seems to be a good limit, letting you see the processes that are consuming the most resources without trapping everything.
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