10Feb 2020 by Grant Fritchey 7 Comments

Extended Events: Histogram Output

SQL Server, You Can't Do That In Profiler
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…
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03Feb 2020 by Grant Fritchey 14 Comments

Profiler: Time To Go

SQL Server
I've decided that, in fact, it is time to start moving people off the ancient technology, Profiler. Before, I always said, stay where you're comfortable. However, keeping people comfortable means that they're also going to keep promoting Profiler/Trace to new people on new platforms. That is a real problem. To fix the problem of old school, slow, inferior, methods of data collection, troubleshooting, and consuming metrics, we need to educate people. Extended Events are not simply a replacement for Trace. They're not simply another way to gather query metrics. No, in fact, this is a whole new tool, with new functionality and a very high level of support and engagement from Microsoft. Extended Events are where all new functionality since 2012 provides mechanisms for monitoring behavior. As technologists we should…
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27Jan 2020 by Grant Fritchey 9 Comments

Extended Events Misperceptions: Profiler is Easier, Part 2

SQL Server, Tools
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…
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21Jan 2020 by Grant Fritchey No Comments

Microsoft Tools That Help Query Tuning

SQL Server, T-SQL, Tools
Query tuning is not easy. In fact, for a lot of people, you shouldn't even try. It's much easier to buy more, bigger, better hardware. Yeah, the query is still slow on newer, faster hardware, but not as a slow as it was. However, sooner or later, you're going to have to start to spend time fixing queries. In fact, you can find that fixing queries actually is more cost effective than buying more hardware. The problem is, query tuning is not easy. So, what do you do? Microsoft Can Help There are a number of tools available to you, right now, provided by Microsoft that can help you better and more easily tune your queries. This ranges from extended events to query store, and absolutely includes execution plans and…
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20Jan 2020 by Grant Fritchey 10 Comments

Extended Events Misperceptions: Profiler is Easier

SQL Server
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,…
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13Jan 2020 by Grant Fritchey 4 Comments

Causality Tracking in Extended Events

SQL Server
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…
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16Dec 2019 by Grant Fritchey 53 Comments

Why Don’t People Use Columnstore Indexes?

Professional Development, SQL Server
I saw this question on SQL Server Central the other day and had an immediate, visceral reaction. I know why. Now, before I explain my answer, please, let me reassure you. I get it. You're busy. What I'm about to suggest is not meant as a direct critique of you. It's just an observation of the human condition. Heck, maybe I'm wrong. So, before you write the angry screed about how busy you are and why you can't possibly do what I'm about to suggest, believe me, I already understand. I'm still going to suggest something that's going to make some of you angry. Common Knowledge If you'll permit me, I want to talk about Extended Events before we talk about Columnstore. SIDE NOTE: Standing invitation, any time I'm at…
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19Aug 2019 by Grant Fritchey 19 Comments

Profiler and Trace vs. Extended Events

SQL Server
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…
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03Jun 2019 by Grant Fritchey 2 Comments

Which Query Used the Most CPU? Implementing Extended Events

SQL Server, T-SQL, Tools
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…
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04Mar 2019 by Grant Fritchey 4 Comments

system_health Extended Events in Azure SQL Database

Azure, SQL Server
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…
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