I'm running a data import (using C#/Linq), and naturally I'm trying to optimize my queries as much as possible. To this end I'm running a trace on the DB using SQL Server Profiler, with my trace filtered by my SQL login name (it's a name that can uniquely be attributed to my data import process).
Strangely enough, most of my SQL statements are really quick :) - very few queries even break over the 1ms mark. But spaced in between all my queries are several rows where the EventClass is "Audit Login" or "Audit Logout" - and the duration of an "Audit Logout" can be up to a minute!
Has this got something to do with the fact that I'm using transactions in my import? If so, is there any way to find which are the big-hitting queries so I can clean those up?
If I remember correct, the duration of an Audit Logout is the amount of time the connection was open. E.g. nothing to do with speed of the command - just the amount of time the login was 'logged in'.
Login/Logout events are related to the setting up / tearing down. IIRC the time is the 'was logged in for time' as opposed to a processing duration as with other log events.
In general, one hides these events unless you suspect there's an issue with connection pool management etc.
The raw times for the batches should be sufficient to diagnose the time the actual activity is taking including the impact of any transactions etc.
The Audit Logout event class indicates that a user has logged out of (logged off) Microsoft SQL Server. Events in this class are fired by new connections or by connections that are reused from a connection pool.
it's the total time the connection was logged in for, including idle time, so it doesn't indicate a performance problem. Also profiling logins/logouts is very unlikely to cause a performance problem. You'd be better off looking for poorly performing queries, possibly long-running queries.
For more info i suggest https://msdn.microsoft.com/en-us/library/ms175827.aspx :)
Also worth noting as in this answer that Audit Login/Logout may just mean the connection is being reused from / returned to the connection pool.
来源：https://stackoverflow.com/questions/2132539/what-is-audit-logout-in-sql-server-profiler