Optimistic concurrency control, Database Management System

Optimistic Concurrency Control

Is locking the only way to stop concurrency related problems? There exist some other ways too. One such way is known as an Optimistic Concurrency control.

The basic logic in optimistic concurrency control is to permit the concurrent transactions to update the data items supposing that the concurrency related trouble will not occur. Though, we require to reconfirm our view in the validation phase. Thus, the optimistic concurrency control algorithm has the following phases:

a)   READ Phase: In a read phase, transaction T reads the data items from the database into its private workspace. All the updates of the transaction can only alter the local copies of the data in the private workspace.

b)   VALIDATE Phase: Checking is performed to verify whether the read values have changed during the time transaction was updating the local values. This is performed by evaluating the current database values to the values that were read in the private workspace. In case, the values have altered the local copies are thrown away and the transaction aborts.

c)   WRITE Phase: In a write phase, if validation phase is successful the transaction is committed and updates are applied to the database, otherwise the transaction is rolled back.

 

Posted Date: 3/12/2013 3:12:05 AM | Location : United States







Related Discussions:- Optimistic concurrency control, Assignment Help, Ask Question on Optimistic concurrency control, Get Answer, Expert's Help, Optimistic concurrency control Discussions

Write discussion on Optimistic concurrency control
Your posts are moderated
Related Questions
Write the C++ program having class name studentinfo, that is used to store the VU student information: This class should store your VUID, campus id, name and father name in the fol

Explain Relational model and their use in DBMS? Relational Model - The relational model was first introduced through E.F. Codd of the IBM Research in the year of 1970. The mode

Update Anomaly : This anomaly is occurred due to data redundancy. Redundant information makes updates more complex since, for example, varying the name of the instructor of MCS-014

What is the use of unique function? UNIQUE function: If UNIQUE is specified then only unique values are used to computed the mean.

Describe the shadow paging technique.

Which database object does not physically exist? A view database object does not physically exist.

What Is Recovery?  During the life of a transaction, i.e., a after the start of a transaction but before the transaction commits, various changes may be made in a database state

write-set(T): Each data items that are written by a transaction T

What is the meaning of Recovery? In deferred update methods, if a transaction fails before arriving its commit point, it will not have altered the database in any way, so UNDO

Differentiate between static hashing and dynamic hashing.  Ans: Static Hashing comprises the number of primary pages in the directory fixed. So, while a bucket is full, we requ