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!
Types of Locks
There are two necessary types of locks:
Let us first take an instance for binary locking and describes how it solves the concurrency related troubles. Let us reconsider the transactions T1 and T2 for this purpose; though we will add to needed binary locks to them.
Schedule
T1
T2
Lock X
Read X
Subtract 100
Write X
Unlock X
Lock Y
Read Y
Display X+Y
Unlock Y
Add 100
Write Y
Figure: An incorrect locking implementation
Does the locking as completed above solve the problem of concurrent transactions? No the similar problems still remains. Try working with the old value. Therefore, locking should be completed with some logic in order to make sure that locking results in no concurrency related problem. One such answer is given below:
Lock X (issued by
T2)
Lock X: denied as T1 holds the lock.
The transaction T2 Waits and T1 continues.
The lock request of T2 on X can now
be granted it can resumes by locking X
Figure: A correct but restrictive locking implementation
Therefore, the locking as above when you get all the locks at the starting of the transaction and release them at the end ensures that transactions are implemented with no concurrency related problems. Though, such a scheme limits the concurrency. We will talk about a two-phase locking method in the next subsection that gives sufficient concurrency. Though, let us first discuss multiple mode locks.
Discuss the term- Design Optimization We have seen various ways of representing the objects.The fundamental design model uses analysis model as the framework for implementati
We have a buildup of payments that need to be processed. You will need:- To prepare customer account on our site Process payment (you must have working Paypal account to d
Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pictori
what is the relationship between receipt and owner entities in computer sales and service company
Explain P command in the respect of QBE? P: It is the command in which is used to print (logically display) the value of the attribute in whose cell it is writ
The technique of converting the state diagram to code a) Identify all major control paths. Start from initial state; choose a path across the diagram that corresponds to normal
In which format database schema is written ? Data base schema is written in the DDL format.
Removing a Synonym: DROP SYNONYM D30;
This constraint shows that the key attribute value in each tuple must be unique, i.e., no two tuples have the similar value for the key attribute. This is because the value of the
Define the terms 1) physical schema 2) logical schema. Physical schema: The physical schema explains the database design at the physical level, which is the lowest lev
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: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd