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!
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. The database through such a state is in an inconsistent state. What occurs when a failure occurs at this stage? Let us define this with the help of an example:
Suppose that a transaction transfers Rs.2000/- from A's account to B's account. For simplicity we are not showing any error checking in the transaction. The transaction may be written as:
Transaction T1:
READ A
A = A - 2000
WRITE A
→ Failure
READ B
B = B + 2000
WRITE B COMMIT
What would occur if the transaction fails after account A has been written back to database? As far as the holder of account A is concerned s/he has transferred the money but that has never been taken by account holder B.
Why did this trouble occur? Because although a transaction is considered to be atomic, yet it has a life cycle during which the database gets into an inconsistent state and failure has happened at that stage.
What is the solution? In this situation where the transaction has not yet committed the changes made by it, the partial updates require to be undone.
How can we do that? By remembering information about a transaction such as when did it begin, what items it updated etc. All such details are occurred in a log file.
Submit the table creation statements (including constraints) for the Database Model. Submit them all in a single script file. Also submit a document explaining what test data yo
triggering
Define and differentiate between ordered indexing and hashing. Ans: Ordered indexing: To gain fast random access to records in a file, we can make of an index structure. Every
Describe analysis of access paths To describe analysis of access paths, consider an example of the design of a company's employee skills database. A part of the object model fr
I have to solve a problem using access
You have a friend that runs a motor bike club that holds racing events at various venues on weekends, on a monthly basis. Some venues are private race tracks and some are dirt trac
(A) For the relation; CarSales (RegNo, BuyerName, Address, SalesPerson, Make, Model, Commission) The following functional dependences hold, RegNo _ID à Make, Model Reg
We are looking to find someone to prepare a database which improves upon the one we are using at present. The present database will be found here: Click on filter options and yo
Project Description: My VBulletin forum was hacked, and soon after my server machine died. So, I'm now on a new machine, and I think that I've taken care of 99% of the hacking..
Define Network DBMS The NDBMS is built primarily on a one-to-many relationship, but where a parent-child representation between the data items cannot be ensured. This may occur
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