Definicja lock cumulation
Multiple placing of a lock.
A lock cumulation occurs when the name, argument, and lock mode of the elementary locks are all the same. The cumulation counter is increased by 1 after every subsequent cumulation, and is reduced by 1 every time a lock cumulation is released. The lock itself is released when the counter reaches 0.
There are the following types of locks:Shared (read lock):
Multiple transactions can hold a read lock simultaneously (for the purposes of reading data; that is, the data is not changed)Exclusive (write lock):
Simultaneous read or write locks on this object are rejected. Only the lock owner can place further locks. This is known as cumulation.Exclusive but not cumulative lock:
With this type of lock, even the original user can only place it once.Optimistic lock:
Behaves like a shared lock, but is converted into an exclusive lock when the data is actually changed.
Słownik i definicje SAPa na L.