Login Events include Pooled Connections

Every now and then I stumble across something and say "I know I knew this before!"  In Profiler, the Audit Login event includes regular logins and connection pooling reuse.  If you run a trace and see a large number of logins you'll need to include the EventSubClass column to determine if they are pooled connections.

Image of Profiler showing pooled and non-pooled connections

Even more misleading is PerfMon.  If you capture the SQLServer:General Statistics - Logins/sec counter you'll see regular logins and connection pooling reuse.  I haven't found a way to have PerfMon just show me "real" logins and not connection pooling events.  I've started watching User Connections and Logouts/sec to see how many logins are really happening.  Logouts/sec doesn't report anything related to connection pooling.

On SQLTeam.com I have roughly twenty logins per second but under one logout per second while the number of connections is stable.  That tells me I really have one "real" login per second and nineteen connection pooling reuse events per second.

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