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

Explain natural join, Explain natural join? Natural Join - Similar as...

Explain natural join? Natural Join - Similar as equi-join except in which the join attributes (having similar names) are not involved in the resulting relation. Only one sets

What is difference among mysql_connect and mysql_pconnect, What is differen...

What is difference among mysql_connect and mysql_pconnect? Mysql_connect() opens a new connection to the database while mysql_pconnect() opens persistent connection to the data

Represent the form as a relational schema, Question: This form represen...

Question: This form represents one of a number used for each sailing of a range of boats. A passenger may go on many sailings and will have the same passenger number for each.

Convert the erd into its relevant relational schema, Question: Describe...

Question: Describe briefly the three parts of the Relational Model. (a) The term integrity refers to the accuracy or correctness of the data in the database. Define the fol

What is data model, A Data Model in software engineering is an abstract...

A Data Model in software engineering is an abstract model that organizes and documents the business data for interaction between team members and is used as a plan for creating

Column constraints, Column Constraints: NOT NULL, UNIQUE, CHECK, PRIMARY K...

Column Constraints: NOT NULL, UNIQUE, CHECK, PRIMARY KEY, DEFAULT, REFERENCES, On  delete  Cascade :  Using  this  key  whenever  a  parent  row  is  removed  in  a referenced

Adding redundant associations for efficient access, Adding Redundant Associ...

Adding Redundant Associations for Efficient Access Redundant associations do not add any type of information, therefore during design we should actually examine structure of o

Describe disk manager and their work, Describe disk manager and their work?...

Describe disk manager and their work? Disk Manager: Responsible for fetching data regulated through file Manager from disk storage within Main memory and deciding what data to

What are the reasons for having variable length records, What are the reaso...

What are the reasons for having variable length records? What are the various ways to store variable length records? Variable-length records arise in a database in various wa

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