What is pessimistic concurrency? In this approach, each transaction is assigned a timestamp. One can make sure that they are unique using algorithms like Lamport. Here, it is assumed that many users will try to update the data and a deadlock will occur. Hence, it is ensured that only the one who holds the lock over the data can update it.
Locks acquired depend on vendors on the selected isolation level. Some vendors implement ‘Select’ for updating to explicitly acquire a lock.
What is pessimistic concurrency? Pessimistic Concurrency
Pessimistic concurrency is used to lock the resources required for the time span of a transaction’s execution. In this mode, the lock on the record is held until the edit duration is completed. No user is able to get a lock on the same record for the purpose of updating. A transaction is assured of successful completion, unlike dead locks.