Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
Define Join and Outer Join and differentiate between them. Ans: Join - It generates all the combinations of tuples from two relations which satisfy a join condition. Oute
Consider the following frequency counts of some itemsets in a transaction database r : freq({A}, r) = 0.405 freq({B}, r) = 0.510 freq({C}, r) = 0.303 freq({A
Locks: Serialisabilty is just a test whether a given interleaved schedule is ok or has a concurrency related trouble. Though, it does not make sure that the interleaved concurrent
In which form of relational database developer refers to a record? In a tuple form of relational database developer refers to a record.
Write a query that display ename annual salary and comm from emp table
Give the limitations of SQL authorization. The code for checking authorization becomes intermixed with the rest of the application code. Implementing authorization by applic
What is banker's algorithm? Banker's algorithm is a deadlock avoidance algorithm that is applicable to a resource-allocation system with multiple instances of each resource ty
The database depicted in the Visio diagram describes Proceeding , Article , Researcher , article PublishedIn a proceeding, article WrittenBy researchers and proceedings Edi
Consistency error : These errors happen due to the inconsistent state of database caused may be due to wrong implementation of commands or in case of a transaction abort. To overc
Question: a) What is Client/Server and what benefits can be expected from Client/Server systems? b) Explain what middleware is and what it does. Why would MIS managers be p
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd