SQL deadlocks occur when two or more transactions are blocked, each holding a resource that the other transactions are trying to acquire. This creates a cycle of dependencies, causing the transactions to wait indefinitely for each other to release the resources. Deadlocks can significantly impact the performance and efficiency of a database system.
To resolve SQL deadlocks, several strategies can be employed. One common approach is to ensure that transactions always request resources in a consistent order, reducing the likelihood of circular dependencies. Additionally, timeouts can be implemented, where transactions are automatically rolled back if they are unable to acquire the necessary resources within a specified time frame. Monitoring tools can be used to identify and analyze deadlock occurrences, allowing administrators to adjust the system configuration or even manually intervene to break the deadlock. Proper transaction design, isolation levels, and careful consideration of the application's concurrency requirements are crucial in preventing and managing SQL deadlocks.