Unrepeatable reads-problems of concurrent transactions, Database Management System

Assignment Help:

Unrepeatable reads: Assume T7 reads X twice during its implementation. If it did not update X itself it could be very disturbing to see a dissimilar value of X in its next read. But this could occur if, among the two read operations, another transaction modifies X.

 

T7

T8

Assumed value of

X=2000

T7

T8

READ X

 

2000

 

 

UPDATE X

 

3000

READ X

 

3000

 

 

Therefore, the inconsistent values are read and results of the transaction may be in fault.

 


Related Discussions:- Unrepeatable reads-problems of concurrent transactions

Create table and insert data manufacturer-dbms, Create a table according to...

Create a table according to given data:  AmbulanceDriver(Driver_Number#, Name, Address, Birth_Date) AmbulanceDriverTeam(Team_Number#, Driver_Number#, Join_Date, Lea

What is d command work in the respect of qbe, What is D command work in the...

What is D command work in the respect of QBE? D: It is the command inside QBE to delete tuple(s) from the relation.

Define the relations as tables in sql, Consider the relations given below ...

Consider the relations given below Borrower (id_no, name) Book (accno., title, author, borrower_idno) (a) Define the above relations as tables in SQL forming real world assumptio

Serialisable schedules, Serialisable Schedules: If the processes of two tra...

Serialisable Schedules: If the processes of two transactions conflict with each other, how to verify that no concurrency related problems have happened? For this, serialisability t

Shadow paging, Describe the shadow paging technique.

Describe the shadow paging technique.

Order by clause-data manipulation language, Order by clause By usin...

Order by clause By using this rows can be sorted It is used in the last portion of select statement By default it gets ascending order DESC: is used

Sparse and dense indexes, Sparse and Dense Indexes These indexes in pri...

Sparse and Dense Indexes These indexes in principle are the similar as that of indexes used at the back of the book. The key facts of the indexes are: They are arranged

E-commerce and business intelligence systems., Your friend owns and operate...

Your friend owns and operates a wholesale shoe business with annual revenues of $5 million dollars. His wholesale business specializes in supplying and supporting retailers with sh

Er schema, Consider entity type Employee with attributes empNumber (this is...

Consider entity type Employee with attributes empNumber (this is unique), empName, and the year when he/she was hired. An employee can either be a technical employee, a marketing e

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