Category: Profiler

Jason Brimhall shows how Extended Events and server trace events (like Profiler uses) map together:

If you have browsed XEvents to any extent you should probably be familiar with at least one map object that Microsoft has given us. That particular object is sys.dm_xe_map_values and I wrote a bit about it here. That object presents some good information about various data values within XEvents that are delivered with the Event payload as well as some hidden gems that can be extra useful for exploring SQL Server internals. The point is, maps is not necessarily a new concept.

While the concept of a map is not new within XEvents, the implementation in this case is a tad different. You see, the dm_xe_map_values object is more like an EAV object while the map I will introduce today is more of an ordinary lookup table. Let’s take a look.

The map I want to concentrate on for now is the sys.trace_xe_event_map table. You read that correctly – it is a table. We don’t have very many “tables” when dealing with XEvents, but this one happens to be. As Microsoft Docs describes it, the table “contains one row for each Extended Events event that is mapped to a SQL Trace event class.”

Click through for a script which shows how to map them, as well as a couple interesting points.

Erin Stellato wants to know how you use Profiler and server-side traces:

Back in April I wrote a post asking why people tend to avoid Extended Events.  Many of you provided feedback, which I greatly appreciated.  A common theme in the responses was time.  Many people found that creating an event session in Extended Events that was comparable to one they would create in Trace took longer.  Ok, I get that…so as a follow up I am interested in knowing how you typically use Profiler and Trace.  If you would be willing to share that information, I would be extremely grateful.

Head over there and let her know.  For science!

Erin Stellato shows us that Extended Events and Profiler both use local temp storage:

Depending on what events you have configured for Profiler, your filter(s), the workload, and how long you run Profiler, you could generate more events than the UI can handle. Therefore, they’ll start buffering to the User TMP location. If you’re not paying attention, you can fill up the C: drive. This can cause applications (including SQL Server) to generate errors or stop working entirely. Not good.

Reference: https://msdn.microsoft.com/en-us/library/ms174203.aspx

Now, back to the original question. Does the same problem exist for Extended Events? Only if you’re using the Live Data Viewer.  After you have an event session created (you can just use system_health for this example), within Management Studio, go to Management | Extended Events | Sessions, select the session and right-click and select Watch Live Data

This is one of those things you hardly think about, but it makes sense:  that data’s got to be stored somewhere if things are moving too fast for the app.