![]() ![]() We have 3 non-clustered indexes on the table (PID, ACTIVITYID, ITEMID, TRANID), (ITEMID), and (PID, ACTIVITYID). In my simplistic mind these two statements should be locking different rows, and even if they were updating the same row, one should just wait for the other.Ĭan anyone explain why they are causing deadlocks, or give any suggestions as to how to prevent them? I realise some amount of deadlocks are inevitable and the application should handle them (which it does), but I don't understand why they should be happening in this case. UPDATE WF SET QUEUETIME =, STATE =, USER =, TIME = WHERE PID = AND ACTIVITYID = AND ITEMID = AND TRANID = AND STATE = AND USER = nvarchar(4000))UPDATE WF SET QUEUETIME =, STATE =, USER =, TIME = WHERE PID = AND ACTIVITYID = AND ITEMID = AND TRANID = AND STATE = AND USER = ![]() WHERE PID = 'standardOutbound' AND ACTIVITYID = 'Node1' AND ITEMID = '121' AND TRANID = 'toNode1' AND STATE = '' AND USER = '' UPDATE WF SET QUEUETIME=' 13:06:53.625', STATE = 'ready', USER = '', TIME = null WHERE PID = 'MessageProcessing' AND ACTIVITYID = 'Delete' AND ITEMID = '120' AND TRANID = 'Created' AND STATE = 'ready' AND USER = '' UPDATE WF SET QUEUETIME=' 13:06:53.578', STATE = 'outbound', USER = '', TIME = null ![]() For example the two update statements below: New Deadlock Visualizations in SQL Sentry and Plan Explorerĭisclaimer: I used to work for SQL Sentry.I have an application which is running multiple sql statements simultaneously in different threads, causing various deadlocks which all seem to come from one table.As a bonus, these are captured for you automatically on monitored servers without having to configure trace flags, run your own traces, etc.: Have you considered third party monitoring tools? SQL Sentry and Plan Explorer, for example, have a much nicer deadlock graph, showing you object / index names, as well as the order in which the locks were taken. Finding SQL Server Deadlocks Using Trace Flag 1222Īlso note that if your system experiences a lot of deadlocks, this can really hammer your error log, and can become quite a lot of noise, drowning out other, important errors.However, you can run it only for the current running instance of the service (which won't require a restart, but which won't resume upon the next restart) using the following global trace flag command: DBCC TRACEON(1222, -1) I would set this as a startup trace flag (in which case you'll need to restart the service). However, the error log is textual, so you won't get nice deadlock graph pictures - you'll have to read the text of the deadlocks to figure it out. This will write deadlock information to the error log. In order to capture deadlock graphs without using a trace (you don't need profiler necessarily), you can enable trace flag 1222. JOIN sys.dm_exec_connections CN ON CN.session_id = ES.session_idĬROSS APPLY sys.dm_exec_sql_text(CN.most_recent_sql_handle) AS ST JOIN sys.dm_tran_active_transactions AT ON TST.transaction_id = AT.transaction_id JOIN sys.dm_tran_session_transactions TST ON ES.session_id = TST.session_id JOIN sys.dm_exec_sessions ES ON ES.session_id = L.request_session_id JOIN sys.objects O ON O.object_id = P.object_id JOIN sys.partitions P ON P.hobt_id = L.resource_associated_entity_id TST.is_user_transaction as IsUserTransaction, SELECT L.request_session_id AS SPID,ĭB_NAME(L.resource_database_id) AS DatabaseName, The only other way I could suggest is digging through the information by using EXEC SP_LOCK (Soon to be deprecated), EXEC SP_WHO2 or the sys.dm_tran_locks table. You can use a deadlock graph and gather the information you require from the log file. ![]()
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