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

How are tables stored on Disk? We realise that every record of a table can have different amounts of data. This is due to in some records; some attribute values may be "zero".

Conflicting Operations in Schedule: The three simple ways of interleaved instruction implement of transactions T1 and T2. Please note that in the following tables the first col

How does a query tree represent a relational algebra expression?  Discuss any three rules for query optimisation, giving example as to when should each rule be applied.     Ans

Write short note on Data models? Data models: A data model is an abstract model which elaborates how data is represented and accessed. The term data model has two commonly ac

Explain the ACID properties of a transaction Ans: ACID properties are a significant concept for databases. The ACID stands for Atomicity, Consistency, Isolation, and Durability

Define multivalued dependency.  What do understand by trivial multivalued dependency?  Ans: A multivalued dependency is a full constraint among two sets of attributes in a rela

What is Cardinality Ratio? Cardinality Ratios - The cardinality ratios for relationship kinds specifies the maximum number of relationship instances in which an entity can pa

What are the advantages of by using an index and what are its disadvantages ? In difference, if the search key of a secondary index is not a candidate key, it is not sufficient

Decompose the table with the following description and functional dependencies into a set of equivalent tables normalized to 3NF or BCNF. This database stores records from a (ve