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

Write short notes on extension and intension, Write short notes on extensio...

Write short notes on extension and intension? In any data model, it is significant to distinguish among the description of the database and the database itself the description

Create a er diagram to show customer accounts, Information about a bank is ...

Information about a bank is about customers and their account. Customer has a name, address that consists of house number, area and city, and one or more phone numbers. Account ha

The maximum no of key fields that can be used in a header, The Maximum no o...

The Maximum no of key fields that can be used in a header is?? 50

When are they useful justify with an example, When are they useful? Justify...

When are they useful? Justify with an example. The temporary tables are commonly used to support specialized rollups or exact application processing needs. Unlike a permanent t

In case of entity integrity the primary key may be declared, In case of ent...

In case of entity integrity, the primary key may be declared? In a case of entity integrity primary key may be not Null.

How to apply the bcnf decomposition , Consider the following relational sch...

Consider the following relational scheme: R (a,b,c,d,e,f) and its corresponding set of FDs {d→ a, be → c, ac → e, b → f, f → d, a → c}. a. Is the following decomposition i) non

Er digrams, what is er digram given that example of hospital,bank and libra...

what is er digram given that example of hospital,bank and library er digram.

How many levels can be viewed architecture of the database, How many levels...

How many levels can be viewed in Architecture of the database ? Architecture of the database can be viewed as three levels.

Mention the several levels in security measures, Mention the several levels...

Mention the several levels in security measures. A) Database system B) Operating system C) Network D) Physical Human

Describe a technique for direct search, Describe a technique for direct sea...

Describe a technique for direct search? Explain how data is stored within a file so which direct searching can be performed. For a file of unordered fixed length records by u

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