As far as I know, the feature is available in all editions, including Express Edition. How to resolve deadlocks in SQL Server Jby Esat Erkec In this article, we will talk about the deadlocks in SQL Server, and then we will analyze a real deadlock scenario and discover the troubleshooting steps. And event notifications have been available since SQL Server 2005. The automated generation of Deadlock Graph (*.xdl) files is convenient. I think most would agree it's better to know something (bad) happened before the customers start calling. Deadlocks in SQL Server can be a significant challenge for database administrators and developers. On the plus side, I really like the proactive nature: an event occurs, I get an email. (The first time I got deadlock alerts, there were more than 500 of them waiting for me in my Inbox.) Lastly, there's the XML issue: it's not everyone's cup of tea. Additionally, you might get hit with an unexpected deluge of emails. There is an authorization issue for _send_dbmail that will need to be addressed for logins without elevated permissions. The approach presented here may have some drawbacks compared to others. The REPLACE function is used to double up any single quotes that may exist.Īs noted, there are other ways to handle deadlocks in SQL Server. This "query" will be the parameter value for _send_dbmail. Next, we create a "query" that does nothing more than select the data as a string literal. This data will become the contents of a file attachment for an email message. The element and all of its data is assigned to the variable. The XML data returned by the EVENTDATA() function that was written to the QUEUE is assigned to the variable: RECEIVE TOP ( 1 ) - just handle one message at a = CAST ( message_body AS XML ) Fortunately, SQL Server detects this deadlock condition, and selects one of the transactions to be the deadlock victim, terminating that statement and rolling back the changes that it has made. On the queue AND the response wouldn't be sent.ĪLTER QUEUE dbo. At any point before this, weĬould roll back - the received message would be back value ( '(/EVENT_INSTANCE/SessionLoginName)', 'VARCHAR(128)' ) + '' + value ( '(/EVENT_INSTANCE/ServerName)', 'VARCHAR(128)' ) + '' + Now open two instances of SQL Server Management Studio and from instance 1 execute the spTransaction1 stored procedure and from the second instance execute the spTransaction2 and you will see there is no deadlock and both the transactions are executed successfully. value ( '(/EVENT_INSTANCE/EventType)', 'VARCHAR(128)' ) SET = 'SET NOCOUNT ON ' + CHAR ( 13 ) + CHAR ( 10 ) + SET = REPLACE (, CHAR ( 39 ), CHAR ( 39 ) + CHAR ( 39 )) query ( '/EVENT_INSTANCE/TextData/deadlock-list' ) AS NVARCHAR ( MAX )) value ( '(/EVENT_INSTANCE/StartTime)', 'VARCHAR(128)' ) ĭECLARE DATETIME = NVARCHAR ( 255 )= 'Deadlock Graph ' + value ( '(/EVENT_INSTANCE/IsSystem)', 'VARCHAR(8)' ) ĭECLARE VARCHAR ( 128 ) =. value ( '(/EVENT_INSTANCE/LoginName)', 'VARCHAR(128)' ) ĭECLARE INT =. ), TIMEOUT 1000 - if the queue is empty for one second, give UPDATE and go awayĭECLARE SYSNAME =. RECEIVE TOP ( 1 ) - just handle one message at a = CAST ( message_body AS XML ) Receive the next available message FROM the queue * Purpose : Handles deadlock events (activated by QUEUE queDeadlockNotification) TO SERVICE 'svcDeadlockNotification', 'current database' Create the event notification for Deadlock events on the service. Create a service just for Deadlock events. That's rather unusual without a query hint.-Create a queue just for Deadlock events. You are asking for an exclusive lock on a select statement. in the middle of it that makes me think this isn't the whole query) I'm curious as to what else is going on. Without the actual queries there is no way to give you more specific advice.Įdit: Based on the portion of the query you've given above (note there is a. The solution is to either not run the queries at the same time, make them run faster/hold the locks for less time or modify the queries to not use the other table. Note that Table 1 or Table 2 could be just a portion of the tables or even a portion of the same table. SQL Server notices this and kills one of them as the deadlock victim. Each query is going to wait until it can get access to the other table until either the query is canceled, the connection killed or the instance shut down. This creates a situation that can never be resolved. Query 2 has locked Table 2 and wants access to Table 1.Query 1 has locked Table 1 and wants access to Table 2.
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