diagnose-blocking-and-deadlocks

Finds who is blocking whom on Azure SQL Database right now, and reads a completed deadlock graph out of the database-scoped Extended Events session that captured it. Use when someone reports a query or app that hangs under load, pastes "Msg 1205" or "was deadlocked on lock resources", asks who is blocking a session, or ran a blocking query that came back empty and assumed nothing was blocked. Covers which grant a login needs to see another session's blocking and why that differs on Basic, S0, S1 and elastic pools, why an idle session holding a transaction is a head blocker that never appears in sys.dm_exec_requests, and how optimized locking's wait types differ. Does not tune an unblocked query (diagnose-slow-query), diagnose CPU, memory or IO pressure (diagnose-resource-pressure), build or repair the session (capture-with-extended-events) or read the plan (read-execution-plan).