![]() ![]() Query Plan: DELETE FROM StylinInfoTemp FROM AS temp WHERE temp.afid = StylinInfoTemp. SQL Server handles deadlocks by terminating and rolling back transactions that were started after the first transaction. When this stored proc executes I am getting a deadlock on the same page, I am having trouble understanding how exactly is this leading to a deadlock and why do we have same page Id belowĬan someone help me understanding why deadlock, why same page id, how can two process hold and request for the same page id at the same time(image above) and how can I resolve this During the execution we saw some deadlocks because 2 transactions block each other from continuing because each has locked a database resource that the other transaction needs. However the stored procedure tempTable will always have unique afid. You can also delete in batches which will improve concurrency and if the delete is. A deadlock graph will show that, try starting a SQL Server trace grabbing just the Deadlock graphs from the server and check those. In addition on my latest run through of this I had to find and kill the one user connection before any of the above would work. However StylinInfoTemp table may have duplicate entries on afId and ccid. There is the possibility that you are getting lock escalations onto the table level, or page locks on the clustered index page. ALTER DATABASE YourDBName SET MULTIUSER WITH ROLLBACK IMMEDIATE. TempTable in itself can never have duplicate entries. This tempTable is populated on the input received by the stored proc. Here is the schema for tempTable (afid INT, ccid INT) This could mean using faster processors, faster drives, or just installing more RAM.I have a stored procedure which ran parallely by two processes. If this is the case (the above questions will help you determine that) then you'll want to move the DB to a server that is properly sized for the amount of data (and queries) you are trying to process. It's entirely possible that you have finally reached those hardware limits where performance is dropping off radically. Is the DB server's network bandwidth to small to handle transferring the data in a timely manner?Īt the end of the day, it sounds like the machine you are hosting SQL Server on is under sized for what you are trying to do. ![]() Is the DB server essentially out of memory? SQL Server will attempt to allocate every single byte it can, but if it's at capacity and your queries require more data to be loaded then it has to fallback to using virtual memory, which radically increases the amount of time even simple queries might take. If you aren’t familiar with gap locks, you can read an introduction to them in the MySQL docs and their explanation why it is used. This plays an important role in the deadlock, which (SPOILER ALERT) is caused by a technique known as a gap lock. I dont understand why these deadlocks are occurring as its a simple insert where the table only has 1 unique key. Note that we have the key sobjectstartenddeleted which is a non-unique index. The only primary/unique key I have is 'id' which auto increments with each insert. All Im doing is inserting data into a table. Is the DB on a server dedicated to just running SQL Server? If not, other processes might be interferring by stealing precious processor time. I have this set to 10 but Im getting a lot of deadlock errors. My SSRS reports that run on objects in this database are no longer completing. Now there can be a clash also if they are updating adjacent rows. With only row locks, there can only be a clash if they try to update the same row. When I attempt to view the hierarchy trees for tables, views, or procedures in SSMS Object Explorer, I get lock request time out period exceeded. HOLDLOCK is a synonym to SERIALIZABLE, and this isolation level leads to range locks which are wider that strict row locks. There are so many things this could be that all I can offer are a few questions to help guide you towards an answer. I can run basic queries, albeit much slower than normal. To see why check Brent Ozar's insightfull articleĪnyway, you can get a list of long lasting pending transactions using the following query. As many had already pointed-out, usually there's a long lasting transaction, mostly caused my the miss used SET IMPLICIT TRANSACTIONS ON, which should not be used at all. ![]()
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