https://www.sqlserver70.com/tags/head-blocker/Recent content in Head Blocker on SQL Server ScriptsHugo -- gohugo.ioenSQLServer70.comSun, 01 Mar 2026 00:00:00 +0000https://www.sqlserver70.com/post/sql-server-blocking-detection-find-blocked-sessions/Sun, 01 Mar 2026 00:00:00 +0000https://www.sqlserver70.com/post/sql-server-blocking-detection-find-blocked-sessions/ <p>Blocking happens when one session holds a lock that another session needs, so the second session waits. The query below lists every request that is waiting on another session right now: who is blocked, who is blocking, the wait type and wait time, the database, and the SQL text on both sides.</p> <script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-1012089347386563" crossorigin="anonymous"></script> <ins class="adsbygoogle" style="display:inline-block;width:728px;height:90px" data-ad-client="ca-pub-1012089347386563" data-ad-slot="8593449130"></ins> <script> (adsbygoogle = window.adsbygoogle || []).push({}); </script> <h2 id="purpose-and-overview">Purpose and Overview</h2> <p>The finding that matters in a blocking incident is the head blocker, the one session at the front of the chain that is not itself waiting on anyone. Everything behind it is a symptom. <code>sys.dm_exec_requests</code> carries the <code>blocking_session_id</code> column that links each waiting request to the session it is waiting on, and joining it to <code>sys.dm_exec_sessions</code> and <code>sys.dm_exec_sql_text</code> turns that single column into a readable list of victims, owners and statements.</p>