When are two schedules said to be view equivalent, Database Management System

Assignment Help:

When are two schedules said to be view equivalent?    

Ans: Two schedules that is denoted as S and S' are said to be view equivalent if the subsequent three conditions are met

1)  For every data item Q, if a transaction Ti reads the initial value of Q in schedule S, after that transaction Ti should in schedule S'  also read the initial value of Q.

2)  For every data item Q, if a transaction Ti executes read(Q)  in schedule S and that value was generated by Tj (if any) , then transaction Ti must in schedule S'  as well read the value of Q generated by Tj.

3)  For every data item Q, if a transaction if any that carries out the final write(Q) in schedule S should perform the final write(Q) in schedule S'.


Related Discussions:- When are two schedules said to be view equivalent

Describe the different raid levels, Describe the different RAID levels.  Di...

Describe the different RAID levels.  Discuss the choices of the different RAID levels for different applications.          Ans:   There are several combinations of these approa

Define 2nf normal form, 2NF Normal Form : A relation schema process R i...

2NF Normal Form : A relation schema process R is in 2NF if it is in 1NF and each non-prime attribute A in R is fully functionally related on primary key. Second normal form (2N

What is vertical fragmentation, What is vertical fragmentation? Vertica...

What is vertical fragmentation? Vertical fragmentation divides the relation by decomposing the scheme R of relation r.

Entities, Entities Let us first be aware of the question: What are e...

Entities Let us first be aware of the question: What are entities? An entity is an object of concern used to show the things in the actual world, e.g., table, car, bo

4, explain the level architectures of the database management system

explain the level architectures of the database management system

Many-to-many relationship, For each m:n relationship type R, we make a new ...

For each m:n relationship type R, we make a new table (say S) to represent R. We also contain the primary key attributes of both the participating entity types as a foreign key att

The need for three level architecture, The need for three level architectur...

The need for three level architecture The aim of the three level architecture is to divide each user's view of the database from the way the database is physically shown.

Explain nested relations, Explain nested relations? Nested relations ...

Explain nested relations? Nested relations The assumption of INF is a natural one in the bank examples we have considered. However, not all applications are best modelled

Why containment is important in oosystems, Why containment is important in ...

Why containment is important in oosystems? Containment is an significant concept in oosystems because it allows dissimilar users to view data at different granularities.

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