Explain the timestamps for read operations, Database Management System

Assignment Help:

Timestamps For Read operations:

If TS (T) < W-timestamp (Q), then the transaction T is trying to read a value of data item Q which has already been overwritten by some other transaction. As the value which T wanted to read from Q does not be there anymore, and T would be rolled back.

If TS (T) >= W-timestamp (Q), then the transaction T is trying to read a value of data item Q which has been written and committed by some other transaction earlier. As T will be allowed to read the value of Q, and the R-timestamp of Q should be updated to TS (T).

 


Related Discussions:- Explain the timestamps for read operations

What is the meaning of data independence, What is the meaning of Data indep...

What is the meaning of Data independence? Data independence means a programs that are not dependent on the physical attributes of data and a programs that are not dependent on

Special workarea for interface, While using extract datasets it is required...

While using extract datasets it is required to have a special workarea for interface False.  It is not required to have a special workarea for interface

Type of views-data control, Type of views :  Simple views and Difficult ...

Type of views :  Simple views and Difficult Views Feature Simple Views Complex Views Number of tables One

What are the functions of an accumulator, What are the functions of an accu...

What are the functions of an accumulator? The accumulator is the register associated with the ALU operations and sometimes I/O operations. It is an integral part of ALU. It hol

Describe specialsation and generalization, Describe Specialsation and gener...

Describe Specialsation and generalization? Specialisation /generalization: This is a top down and bottom up approach to the design of database. It displays the IS_A relation

Relational constraints, Relational and E-R Model There are three types o...

Relational and E-R Model There are three types of constraints on relational database that have: DOMAIN CONSTRAINT PRIMARY KEY CONSTRAINT INTEGRITY CONSTRAINT

Normalization, Process of normalization is the integral part of designing a...

Process of normalization is the integral part of designing a database. Justify this statement with suitable database design

Objectives-database recovery and security, Objectives Define the te...

Objectives Define the terms RECOVERY and INTEGRITY; Define Recovery Techniques; Explain Error and Error detection techniques, and Define types of Authorisation.

Illustrate different types of locks in sql server, Illustrate different typ...

Illustrate different types of Locks in SQL Server. There are three kinds of locks in SQL Server i.) Shared locks - These are used for operations which don't allow any update

What is a database, What is a Database? To know what database is, we ha...

What is a Database? To know what database is, we have to start from data, which is the basic building block of any DBMS. Data: Facts, figures, statistics etc. having no pa

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