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

Define tuple variable, Define tuple variable Tuple variable is a type o...

Define tuple variable Tuple variable is a type of variable whose domain is the set of all tuples.

Which data type can store unstructured data, Which data type can store unst...

Which data type can store unstructured data? Raw data type can store unstructured data.

What are domain constraints, What are domain constraints?  A  domain is...

What are domain constraints?  A  domain is  a  set  of  values  that  might  be  assigned to an attribute  .all  values that appear in a  column of a relation must be taken fro

Describe second normal and third normal form, Database Management Systems ...

Database Management Systems 1. Explain SQL Server 2000 Architecture with diagram. 2. Describe Second Normal and Third Normal Form. 3. Explain about query engine and stora

Datawarehouse, 1) Define a job scheduling strategy that will meet business ...

1) 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 pict

Relation schema for student, Example RELATION SCHEMA for STUDENT: STU...

Example RELATION SCHEMA for STUDENT: STUDENT (Roll No: string, name: string, login: string, age: integer) RELATION INSTANCE

How does query tree represent relational algebra expression, How does a que...

How does a query tree represent a relational algebra expression?  Discuss any three rules for query optimisation, giving example as to when should each rule be applied.     Ans

Central database schema, Show a centralised schema to support the operation...

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

Data models, why older data models are being replaced by new data models....

why older data models are being replaced by new data models.

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