The concurrent transactions, Database Management System

Assignment Help:

The Concurrent Transactions

 Almost every commercial DBMS support multi-user environment. Therefore, allowing multiple transactions to proceed concurrently. The DBMS must make sure that two or more transactions do not obtain into each other's way, i.e., transaction of one user doesn't effect the transaction of other or even the transactions issued by the similar user should not get into the way of each other. Be advised that concurrency related problem may happen in databases only if two transactions are contending for the similar data item and at least one of the concurrent transactions wishes to update a data value in the database. In this, the concurrent transactions only read similar data item and no updates are done on these values, then it does NOT create any concurrency related difficulty. Now, let us talk about why you require a mechanism to control concurrency.

Consider a banking application dealing with saving and checking accounts. A Banking Transaction T1 for Mr. Sharma moves Rs.100 from his checking account balance X to his savings account balance Y, using the transaction T1:

Transaction T1:

A:  Read X

Subtract 100

Write X

B:   Read Y

 Add 100

Write Y

Let us assume an auditor wants to know the total assets of Mr. Sharma. He implements the following transaction:

Transaction T2:

Read X Read

Y Display

X+Y

Assume both of these transactions are issued concurrently, and then the implement of these instructions can be combined in many ways. This is also known as the Schedule. Let us describe this term in more detail.

A schedule S is described as the sequential ordering of the operations of the 'n' interleaved transactions. A schedule keeps the order of operations within the individual transaction.

 

                       5_The Concurrent Transactions.png

                   One possible schedule for interleaved execution of TA and TB


Related Discussions:- The concurrent transactions

ERD, A student entity type has the following attributes,name..

A student entity type has the following attributes,name..

Economics, Economics: It is now usually accepted that it costs less to make...

Economics: It is now usually accepted that it costs less to make a system of smaller computers with the equivalent power of a one large computer. It is more cost-effective to get s

What are the advantages of embedded query language, What are the advantages...

What are the advantages of embedded query language? Give an example of an embedded SQL query. Embedded query language - SQL could be implemented within two ways. It can be us

Secondary indexes, Secondary Indexes Let consider the student database ...

Secondary Indexes Let consider the student database and its clustering index and primary (only one will be applicable at a time). Now consider the state when the database is to

Describe the strategies adopted by the ministry of ict, Question 1: (a)...

Question 1: (a) Planning and management of ICT projects have a very poor record in developing countries. Briefly explain five critical success factors for correct implementa

File handling and classes, Write the C++ program having class name studenti...

Write the C++ program having class name studentinfo, that is used to store the VU student information: This class should store your VUID, campus id, name and father name in the fol

Data analysis and design, give some example real-life situations where DBMS...

give some example real-life situations where DBMS are most suiitabe

Explain the equijoin, Explain the θ-join and equijoin Refer tables Car ...

Explain the θ-join and equijoin Refer tables Car and Boat which list models of cars and boats and their relevant prices. Assume a customer wants to buy a car and a boat, but sh

Extended e-r features, Although, the essential features of E-R diagrams are...

Although, the essential features of E-R diagrams are enough to design many database situations. Though, with more difficult relations and advanced database applications, it is need

Aims of the design project, The aims of the project are: 1. To enable th...

The aims of the project are: 1. To enable the students to undertake the detailed design of a specific plant or process 2. The design projects includes: process selection; und

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