The single most important thing to remember about Extended Events is that this functionality is not simply a replacement for Profiler/Trace, but a whole new tool with new functionality. My first example for functionality that you simply cannot get in Profiler/Trace is the ability to output to a Histogram. Profiler/Trace can output to a table or to a file. Extended Events can have a target that is a file, same as Profiler. However, you can also have a target: etw_classic_sync_targetevent_counterhistogrampair_matchingring_buffer Read about each of the types in the Microsoft documentation here. I'm going to focus for the moment on the histogram target because it lets you do some fun stuff and easily collect data that you simply can't collect using Profiler/Trace without hopping through a bunch of flaming hoops. Setting…
I wrote a short blog post about the misperception that Profiler was easier than Extended Events when it came to the core concept of "click, connect, BOOM, too much data". Go read it if you like, but I don't think it's actually an effective argument for how much easier Extended Events is than Profiler. Here, we're going to drill down on that concept in a real way. Let's start with a little clarification. I'm going to be a little lazy with my language. Trace is a scripted capture of events on a server. Profiler is a GUI for consuming a Trace, either live or from a file, and for creating Trace events. However, almost everyone refers to 'Profiler' when they mean either Trace or Profiler. I may do the same…
I know, I know, I'm on #teamexevents so I think that Extended Events can do no wrong, but let's address this thought that Profiler is easier. Now, if we're strictly talking knowledge, sure, if you've got a lot of experience with Profiler/Trace and very little with Extended Events, of course Profiler is easer. However, what I'm told is that Profiler doesn't require very much set up, while Extended Events does. That's just wrong, but let's put it to the test. The Test For the comparison, we're not going to do anything special with either tool. I'm just going to start collecting query data with the fewest possible clicks and/or key strokes. I'm going to use both tools short cuts to make this as fast as possible. The goal is, click,…
If you go through all the stuff I've written about Extended Events, you'll find that I use causality tracking quite a bit. However, I've never just talked about what causality tracking is and why I use it so frequently. Let's fix that issue now. Causality Tracking Causality tracking is quite simple to understand. It's property that you set for a given session. A session, of course, is defined by one or more events and a target. You can define things about a session, like it's name, when you define the session itself. Turning on, or enabling, causality tracking is just a matter of defining that the session will have causality tracking. It looks like this in the GUI: It looks like this in the T-SQL code: CREATE EVENT SESSION QueryBehavior…
It's a running joke among the more experienced (read, older) Microsoft Data Platform specialists as to whether you're #teamprofiler or #teamexevents. I'm very much #teamexevents, but I really don't care that you're #teamprofiler. If you want to use the old way of doing things, that's fine. However, I do have a bone to pick. Why on earth would you recommend to new data professionals working on modern systems, let's say at least 2016 or better, who are just getting going on this journey, that they should be using Trace? What are you smoking? Trace vs. Extended Events We're not just talking about where you are comfortable. I get it. You've used Trace/Profiler for 20+ years. Getting it going is all muscle memory. That's fine. As the kids say, you do…
A question that comes up on the forums all the time: Which query used the most CPU. You may see variations on, memory, I/O, or just resources in general. However, people want to know this information, and it's not readily apparent how to get it. While you can look at what's in cache through the DMVs to see the queries there, you don't get any real history and you don't get any detail of when the executions occurred. You can certainly take advantage of the Query Store for this kind of information. However, even that data is aggregated by hour. If you really want a detailed analysis of which query used the most CPU, you need to first set up an Extended Events session and then consume that data. A…
The system_health Extended Events session is incredibly useful. Further, it's running, by default, in every server you have under management that is 2008 or greater. Things are not the same in Azure though. system_health in Azure SQL Database If you look at the documentation for system_health, it shows that it's applicable to Azure SQL Database. However, if you try to run the example query, it won't work. This is because the implementation of Extended Events inside Azure SQL Database is a little different. Instead, you need to use the Azure SQL Database equivalent system views to create the same query like this: SELECT CAST(dxdst.target_data AS XML) FROM sys.dm_xe_database_session_targets AS dxdst JOIN sys.dm_xe_database_sessions AS dxds ON dxds.address = dxdst.event_session_address WHERE dxds.name = 'system_health'; Now, running this in Azure, prepare to be…
I'm going to start with a sentence that makes a lot of people crazy; As a DBA and database developer, I love Entity Framework. That's right. Entity Framework is the bomb. It's amazing. It does wonderful stuff. Entity Framework makes the developers lives and jobs easier. It makes my life and job easier. Yes, Entity Framework will improve your job quality and reduce stress in your life. With one caveat, it gets used correctly. That's the hard part right? There is tons of technology that makes things better, if used correctly. There are all sorts of programs that make your life easier, if used correctly. Yet, all of these, used incorrectly, can make your life a hell. One nit that I've always had with Entity Framework is that it's very…
Using the appropriate data type to avoid conversions or implicit conversions is a fundamental approach to good T-SQL coding practices. Implicit conversions can lead to poor performance. However, other than looking at every execution plan in your system, is there a way to see if you are experiencing implicit conversions? Actually, yeah, it's right there in Extended Events. plan_affecting_convert Built right into the Extended Events is an event that captures conversions that would affect execution plans, plan_affecting_convert. This event will show both CONVERT and CONVERT_IMPLICIT warnings that you would normally only see within an execution plan. You can capture this event with others. Capturing events together along with causality tracking makes it very easy to track queries that have the issue. Here's one example of how you might capture implicit…
One complaint I've received frequently is that you can't see stored procedure parameter values in Extended Events. That is patently not true. However, it does depend on where and how you capture the events and which stored procedure parameter values you're going for. I think this is a holdover from 2008 when Extended Events... well, let's be kind and say... didn't work well. Now, they do. Let's explore this a little. Capturing Stored Procedure Executions As with most things, there's more than one way to capture stored procedure execution in Extended Events. First up, it depends entirely on how they're called and on your intentions when you capture the information. Here are the three methods I know to capture just the completion metrics on stored procedure calls: rpc_completed sql_batch_completed module_end…