Shared lock (S lock) and exclusive lock (x Lock)

shared lock (S lock) and exclusive lock (x Lock) Category: Database 2008-11-07 10:53 4409 people read reviews (2) favorite report

Shared lock "s lock"
Also called a read lock, if the transaction T with the data object a plus s lock, then the transaction T can read a but cannot modify a, the other transaction can only a plus s lock, and cannot add x lock, until T release S lock on A. This ensures that other transactions can read a, but cannot make any modifications to a before T releases the S lock on a.

Exclusive lock "x lock"
Also known as write lock. If the transaction t has an X lock on the data object A, the transaction T can read a or modify a, and the other transaction cannot add any locks to a, until T releases the lock on A. This ensures that the other transaction cannot read and modify a until the lock on the A is released by T.

Shared lock (S lock) and exclusive lock (x Lock)