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

Writing a pl/sql program, Problem 1. Create a PL/SQL program to insert ...

Problem 1. Create a PL/SQL program to insert data into student table and display the details of the student having Reg.No 1010 Writing a PL/SQL program to Insert data

What are stand-alone procedures, What are stand-alone procedures? Proce...

What are stand-alone procedures? Procedures that are not part of a package are called as stand-alone because they independently defined. A good example of a stand-alone procedu

Improved reliability, Improved Reliability: In a centralised DBMS, a server...

Improved Reliability: In a centralised DBMS, a server failure stops the operations of the DBMS. Though, a failure at single site of a DDBMS, or a failure of a communication link cr

Explain about sql server 2000, What is the difference between SQL Server 2...

What is the difference between SQL Server 2000 complete and differential backups? A complete backup makes a copy of the whole database. A differential backup creates a copy of

What are the drawbacks of shadow-paging technique, What are the drawbacks o...

What are the drawbacks of shadow-paging technique? The drawbacks of shadow paging is:- a) Commit Overhead b) Data fragmentation c)  Garbage collection

What is persistency, What is persistency? Persistency ensures which dat...

What is persistency? Persistency ensures which data is stored and that after the object is no longer available (program stops running) the data will be available to other users

What is interaction diagram, What is Interaction Diagram An interactio...

What is Interaction Diagram An interaction diagram shows an interaction, comprises of a set of objects and their relationships including the messages that may be dispatched be

Queries, Write a query that display ename annual salary and comm from emp t...

Write a query that display ename annual salary and comm from emp table

Define query optimization, Define query optimization. Query optimizatio...

Define query optimization. Query optimization refers to the process of search the lowest -cost method of evaluating a given query.

ER DIAGRAM, draw ER diagram of student entity and course entity where attri...

draw ER diagram of student entity and course entity where attribute of student entity are student roll, student name, student phone and student address and attribute of course enti

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