Wound-wait scheme-deadlock prevention, Database Management System

Assignment Help:

"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.


Related Discussions:- Wound-wait scheme-deadlock prevention

Explain data models namely relational network - hierarchical, Explain the t...

Explain the three data models namely relational, network and hierarchical and evaluate their relative advantages and disadvantages. Hierarchical Model: In hierarchical model, da

Example of equijoin, Example: Consider the following relations: ...

Example: Consider the following relations: ROLLNO NAME ADDRESS COURSE_ID 100 Ka

Er database theoretical and modeling database system, Need an expert in ER ...

Need an expert in ER database theoretical and modeling database system Project Description: Need an expert in ER database theoretical and modeling database systems? Skills

Differentiate between natural join and outer join, Differentiate between na...

Differentiate between natural join and outer join? Natural join is a binary operator which is written as (R * S) where as R and S are relations. The output of the natural join

Differance between open addressing and chaining collision, Differance betwe...

Differance between Open addressing and chaining for collision resolution ? In open addressing , proceeding from the occupied position specified by hash address the program che

Define partial key and primary key, Define Partial Key and Primary Key ...

Define Partial Key and Primary Key A partial key, also known as discriminator, is the set of attributes which can uniquely identify weak entities that are related to similar o

Define the boyce-codd normal form, Define the Boyce-Codd Normal Form with i...

Define the Boyce-Codd Normal Form with instance and also Compare BCNF and 3NF.  Ans: BCNF: For each functional dependency X->Y in a set F of functional dependencies over relati

Differance between internal and external schema, Differance between interna...

Differance between internal and external schema? Internal and external schema: Internal Schema • Describes the physical storage structure • Uses a physical data model External

Help, #questiononsider the following relation: CAR_SALE =(CAR_ID,oPTION_TYP...

#questiononsider the following relation: CAR_SALE =(CAR_ID,oPTION_TYPE, Option_listpreice, Sale_date, Option_discountedprice)..

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd