Peter already has an exclusive lock on the orders table. For example, if a transaction is waiting for user input and the user goes to lunch or even home for the weekend, the user delays the transaction from completing. For example, a thread in a multithreaded operating system might acquire one or more resources, such as blocks of memory. Parallel query execution-related resources. Deadlocks are resolved almost immediately, whereas blocking can, in theory, persist indefinitely.
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