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

Define view? how it is related to data independence, A View may be defi...

A View may be defined of as a virtual table, that is, a table that does not really exist in its own right but is instead inferred from one or more underlying base data table. T

Distributed transaction atomic-consistent-isolated, A distributed transacti...

A distributed transaction consists of subtransactions that execute at different sites and access local DBMSs at those sites. For example, a distributed transaction that transfers m

ER diagram, #question. acompani datdbase needs to store information about e...

#question. acompani datdbase needs to store information about employees (identified by a social security number,with salary and phone as attributes) and departments (identified by

E-R Diagram, The H. I. Topi School of Business operates international busin...

The H. I. Topi School of Business operates international business programs in 10 locations throughout Europe. The school had its first class of graduates in 1965. The school keep

Keys, it can be possible to create any table without primary key

it can be possible to create any table without primary key

Task partitioning, Task Partitioning, Sequencing and Project Planning T...

Task Partitioning, Sequencing and Project Planning The tasks required for the service might be broadly partitioned into: 0.      Set up database tables and account file

Trigger , Flights(FlightNo, DeptDateTime, Origin, ArrivalDateTime, Destinat...

Flights(FlightNo, DeptDateTime, Origin, ArrivalDateTime, Destination, Capacity, SoldSeats) Tickets(FlightNo, Seat, CustID) Where - flightNo is the PK of the flights table - DeptDa

What is a recovery scheme, What is a recovery scheme? An integral part ...

What is a recovery scheme? An integral part of a database system is a recovery scheme that can restore the database to the reliable state that existed before the failure.

Explain briefly concurrent task by taking an example, Explain briefly concu...

Explain briefly concurrent task by taking an example. Concurrent Task- The concurrent occurrence of more than one event is called concurrent task. Operating systems can handl

Datamodels, explain thee diffrent types of data models

explain thee diffrent types of data models

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