Performance Tuning with SQL Server Dynamic Management Views

Chapter 2: Connections, Sessions and Requests
Identify idle sessions with orphaned transactions
The following query joins sys.dm_exec_sessions to sys.dm_exec_requests and
sys.dm_tran_session_transactions. The requests DMV will be discussed in
more detail shortly, and the session_transactions DMV will be introduced fully in
Chapter 4.
The inner join to sys.dm_tran_session_transactions returns all sessions with
corresponding open transactions. By performing a left join to sys.dm_exec_requests
and returning results where a NULL foreign key is encountered, we limit the results to
only those sessions that have open transactions, yet no corresponding request associated
with the session.
SELECT des.session_id ,
des.login_time ,
des.last_request_start_time ,
des.last_request_end_time ,
des.host_name ,
des.login_name
FROM sys.dm_exec_sessions des
INNER JOIN sys.dm_tran_session_transactions dtst
ON des.session_id = dtst.session_id
LEFT JOIN sys.dm_exec_requests der
ON dtst.session_id = der.session_id
WHERE der.session_id IS NULL
ORDER BY des.session_id
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