This is Josh’s feature, since we wrote most of the code for it together. Basically, it recognize a very common performance problem, queries that uses too many joins, such as this one:

Which would result in the following warning:

Queries with too many joins might be a performance problem. Each join requires the database to perform additional work, and the complexity and cost of the query grows rapidly with each additional join. While relational database are optimized for handling joins, it is often more efficient to perform several separate queries instead of a single query with several joins in it.

For OLTP systems, you should consider simplifying your queries or simplifying the data model. While I do not recommend avoiding joins completely, I strong discourage queries with large numbers of joins. Another issue to pay attention to is possible Cartesian products in queries contains joins, it is very easy to create such a thing and not notice it during development.

One of the things that makes working with the profiler easier is the fact that it gives you not just information, but information in context.

I was working with an app using Rhino Service Bus, and it really bothered me that I couldn’t immediately figure out what was the trigger for a session. When using ASP.Net or WCF, the profiler can show the URL that triggered the request, but when we are not using a url based mechanism, that turns out to be much harder.

So I set out to fix that, you can see the results below:

This session was generated by a message batch containing messages for MyBooks, MyQueue, etc.

The integration is composed of two parts, first, from the profiler perspective, you now have the ProfilerIntegration.CurrentSessionContext property, which allows you to customize how the profiler detects the current context.

The second part is the integration from the application framework itself, you can see how I did that for Rhino Service Bus, which will dynamically detect the presence of the profiler and fill the appropriate values. The result makes it a lot easier to track down what is going on.

The profiler could do session diffs (showing the difference between executed statements between two sessions) for a while now, but we got some requests for changing it to follow a more traditional source control diff style.

This is now done, and it should make it easier to understand the changes between two sessions: