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.