![]() It’s mainly a deadlock that occurs because of a bad indexing strategy. In this section I want to talk a little bit more about the most common ones.Ī typical deadlock that I see at almost every SQL Server installation is the famous Bookmark Lookup Deadlock, which occurs when you have concurrent read and write activity to Clustered- and Non-Clustered Indexes. There are multiple types of deadlocks that can occur in SQL Server. And with the enabled trace flag 1222, SQL Server will log deadlock information into the error log. Extended Events provides you the system_health event session, which tracks historical deadlocks since the last restart of SQL Server. If you are on SQL Server 2008 and higher, you can also use Extended Events to troubleshoot deadlock situations. SQL Server Profiler provides you the Deadlock Graph event, which occurs as soon as a deadlock was detected. You can troubleshoot a deadlock in multiple ways. Of course you should keep track of reoccuring deadlocks, so that you do not retry your transaction over and over again. Resubmit the query, which was rolled back by SQL ServerĪfter the resubmission of the query, the query should continue without any problems, because the other blocking query will have already finished its transaction.Pause the application briefly to give the other query time to complete its transaction and release its acquired locks. ![]() Check for error number 1205, when an exception is thrown.A smart developer must do the following steps to recover from a deadlock: The “nice” thing about deadlocks is that you can fully recover from that error situation without any user interaction. The query which gets rolled back receives the error number 1205. In the worst case, a deadlock should therefore not last longer than 5 seconds. This background process runs every 5 seconds and checks the current locking situation for deadlocks. SQL Server implements the deadlock detection in a background process called the Deadlock Monitor. In the context of SQL Server, the cheapest transaction is the transaction that has written the fewer bytes to the transaction log. To resolve a deadlock, SQL Server has to rollback the cheapest of the 2 transactions. ![]() The nice thing about deadlocks is that SQL Server automatically detects and resolves them. And finally I will show you some specific deadlock types in SQL Server, and how you can avoid and resolve them. In the first step I want to give you an overview how SQL Server handles deadlocks. In todays blog posting I want to talk about how to handle Deadlocks in SQL Server. A deadlock occurs when 2 queries are waiting for each other, and no query can continue its work anymore. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |