Wound-wait scheme-deadlock prevention, Database Management System

"Wound-wait" scheme: It is based on a preemptive method. It is based on a simple rule:

                  If Ti requests a database resource that is held by Tj

                   then if Ti has a larger timestamp (Ti is younger) than that of Tj 

                    it is allowed to wait;

     else Tj is wounded up by Ti.

For example, suppose that 3 transactions T1, T2 and T3 were generated in that series, then if T1requests for a data item which is presently held by transaction T2, then T2 is rolled back and data item is allotted to T1 as T1 has a smaller time stamping than that of T2. Though, if T3 requests for a data item which is presently held by transaction T2, then T3 is permitted to wait.

                                    2389_Wound-wait scheme-deadlock prevention.png

                                                   Figure: Wound-wait Scheme of Deadlock prevention

It is vital to see that whenever any transaction is rolled back, it would not make a starvation condition, i.e., no transaction gets rolled back repeatedly and is never permitted to make progress. Also both "wait-die" & "wound-wait" idea avoid starvation. The number of aborts & rollbacks will be higher in wait-die scheme than in the wound-wait idea. But one main problem with both of these ideas is that these ideas may result in unnecessary rollbacks.

Posted Date: 3/12/2013 3:11:29 AM | Location : United States

Related Discussions:- Wound-wait scheme-deadlock prevention, Assignment Help, Ask Question on Wound-wait scheme-deadlock prevention, Get Answer, Expert's Help, Wound-wait scheme-deadlock prevention Discussions

Write discussion on Wound-wait scheme-deadlock prevention
Your posts are moderated
Related Questions
Deadlock Prevention One of the easiest approaches for avoiding a deadlock would be to obtain all the locks at the begin of the transaction. Though, this approach restricts conc

Question : (a) Database Management Systems (DBMS) is the foundation of business intelligence. Explain the following concepts related to DBMS: (i) Entity Relationship Diagr

we need example of 2phase locking

Explain heap file with advantages? Heap File is an unordered set or a group of records, stored on a set of pages. This class gives basic support for inserting, updating, select

What is primary Key Explain? Primary Key - Primary key is one of the candidate keys. It should be selected such in which its attribute values are never, or very rarely, chang

Define cardinality and participation constraints on a relationship type, completeness constraint on generalization.        Ans: Cardinality defines the number of entities to wh

Show a centralised schema to support the operation of the system you have chosen, including in particular: the product catalogue; the outlets and respective stocks; customer record

Dirty Reads: T10 reads a value which is updated by T9. This update has not been committed and T9 aborts. T9 T10 Value of x old value = 200

Question 1 Explain the concept of database recovery management. Explain the different levels of backup used for recovering data Question 2 What are the different types of par