Search Results for: extended events

Why I Love Extended Events, Reason 394: Customize Live Data

There are so many reasons to love Extended Events that it can really be overwhelming, but, one more reason that I love them are the ability to customize Live Data. More importantly, you can share that customization with others or move it between machines. Let's explore this. Customize Live Data If you open up an Extended Events file, or connect to a running Session, you're looking at the Live Data window and it looks something like this: I won't lie, that's a pretty ugly UI. At the top are all the events you've captured. At the bottom are the event fields. If you want to look at the information in different events, you click on the event, then down at the fields... blech! However, I have some options. Let's right…
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Extended Events, the system_health Session, and Waits

I advocate for, use, document, teach, and just downright love, Extended Events. They are so much better than the old Trace Events (aka, Profiler) that it's sometimes difficult to keep from just gushing. Let's talk about a common situation that you're going to run into on your servers all the time and how you can put Extended Events to work to help you, without actually doing any work at all. What's that? Be lazy and get rewards? Yes. The Extended Events system_health Session On your servers, any of them that are SQL Server 2008 or newer, right now, unless you've performed actions to prevent this, you're running the Extended Events system_health session. It's just happening, currently, on all your servers. Nothing you need to do about it at all. I'll…
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Execution Plan Shortcoming in Extended Events

I use Extended Events almost exclusively for capturing query metrics. They are the most consistent and lowest cost mechanism for getting the time and resources used by a query. They can be filtered, combined with other events, they're just marvelous... until you capture an execution plan. Execution Plans in Extended Events Don't get me wrong. Capturing execution plans with Extended Events is the way to go if you're attempting to automate the process of capturing plans on specific queries on an active system. It's step two that bugs me. So, we capture the plan. Here's an example script. Captures all the various plans and the batch, puts 'em together using causality tracking: CREATE EVENT SESSION ExecutionPlansOnAdventureWorks2014 ON SERVER ADD EVENT sqlserver.query_post_compilation_showplan (WHERE ( sqlserver.database_name = N'AdventureWorks2014')), ADD EVENT sqlserver.query_post_execution_showplan (WHERE…
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Statistics Use, Extended Events and Execution Plans

Query tuning ain't easy. Figuring out which index is getting used is one step, and generally simple, look at the execution plan to see which index is in use and whether it's being used in a SEEK or a SCAN. Done. However, when your index isn't being used, how do you tell how or why something else is being done? Well, that's largely down to row counts which brings us to statistics. Which Statistics are Used Years ago I was of the opinion that it wasn't really possible to see the statistics used in the generation of a query plan. If you read the comments here, I was corrected of that notion. However, I've never been a fan of using undocumented trace flags. Yeah, super heroes like Fabiano Amorim and…
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Get That Profiler Feel in Extended Events

I know. You love Profiler. I hear you. You're wrong, but that's OK. Kidding... mostly. Unfortunately though, I think a lot of what passes for issues and problems with Extended Events is actually a lack of knowledge about how they work. Let's take an example and run with it. No Grid in Extended Events One of the pushbacks I hear about using Extended Events is that the Live Data GUI just doesn't have that neat Profiler grid output. Instead you see a list of events in the top pane and then you have to look at the details in the bottom pane. It looks like this out of the gate: You're right. That's a royal pain. That's it. Toss Extended Events. Back to Profiler. Well, hang on a second. Let's…
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Extended Events and Profiler: XE Profiler

There's a war on in the SQL Server world. On the one side is Profiler (although, really, everyone uses Trace Events). On the other, the "new" (they came out in 2008 with a full GUI in 2012, so...) Extended Events. Lots of people have picked sides on this, including Microsoft. New Trace Events There are none. All the new functionality of every sort from Availability Groups to Query Store to R & Python, have Extended Events created for them. Trace Events, and the technologies supporting them in the form of Profiler, are a dead end. Don't fear. While Trace is on the deprecation list, there doesn't appear to be any fear of that technology being removed completely. At least it won't be removed in the foreseeable future. A future which,…
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Extended Events Data

I’ve been working quite a bit over the last week or so with extended events in Denali. The sheer magnitude of what you can do with extended events is just becoming clear to me. The interesting thing though is how much the basics are similar to trace. Similar mind you, not the same. For example, the best way to gather trace data is to output it to a file and then read the file into a table for later querying. It’s the same with extended events. There’s even a function that acts as a table: SELECT * FROM sys.fn_xe_file_target_read_file ('C:\APath\Query Performance Tuning*.xel', NULL, NULL, NULL); This can take advantage of roll-over files just like the old function used for traces. You can also provide offsets to read a sub-set of…
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Extended Events and Performance Tuning Knowledge

I’m working on updating my book, Query Performance Tuning Distilled, so that it reflects the new things available in SQL Server vNext:Denali. I’m going through the first chapters that are all about gathering information about your systems. Performance tuning is all about building up knowledge of how the system is working in order to understand what you need to change in order to improve it. I’m surprised by how much hasn’t changed. But some of the changes are fundamental and huge. Let’s talk huge. Extended Events is huge. Extended Events came out in SQL Server 2008, but very few people, myself included, paid much attention. Those who did found the implementation awkward and confusing. Only a few people persevered enough to discover just how powerful and amazing these things are.…
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Profiler: Time To Go

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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Microsoft Tools That Help Query Tuning

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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