The locking protocol, Database Management System

The Locking Protocol: To manage concurrency related problems we use locking. A lock is mainly a variable that is associated with a data item in the database. A lock can be located by a transaction on a shared resource that it needs to use. When this is completed, the data item is available for the exclusive use for that transaction that is other transactions are locked out of that data item. When the transaction that has locked a data item does not need to use it any longer, it should unlock the data item so that other transactions can use it. If a transaction attempts to lock a data item already locked by some other transaction, it cannot do so and remains for the data item to be unlocked. The parts of DBMS that controls and stores lock information is known as the Lock Manager. The locking mechanism helps us to change a schedule into a serialisable schedule. We had definite what a schedule is, but what serialisable schedule is?

 

Posted Date: 3/12/2013 1:53:06 AM | Location : United States







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