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What can cause deadlock in SQL?
A deadlock occurs when 2 processes are competing for exclusive access to a resource but is unable to obtain exclusive access to it because the other process is preventing it. This results in a standoff where neither process can proceed. The only way out of a deadlock is for one of the processes to be terminated.
What is deadlock and its condition?
Deadlock is a situation where a set of processes are blocked because each process is holding a resource and waiting for another resource acquired by some other process. A similar situation occurs in operating systems when there are two or more processes that hold some resources and wait for resources held by other(s).
What’s the difference between a deadlock and a lock wait timeout?
Lock wait timeouts and deadlocks both arise from certain locking mechanisms. A lock wait timeout results when one user gets a lock on some data and holds it while another user tries to access it. If the first user doesn’t unlock the data, the second one will time out after a while.
How does a deadlock work in a computer?
A deadlock happens when multiple lock waits happen in such a manner that none of the users can do any further work. For example, the first user and second user both lock some data. Then each of them tries to access each other’s locked data. There’s a cycle in the locking: user A is waiting on B, and B is waiting on A.
Why does my SQL Server database keep deadlocking?
The database engine does not seize up and start deadlocking transactions because it’s tired. Certain conditions must exist in order for a deadlock to happen. Every one of the conditions needs someone, somewhere, to be using the database.
What happens if you wait too long for a lock?
If the first user doesn’t unlock the data, the second one will time out after a while. The database will respond to the second user with an error message saying their lock wait was too long.