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

Describe the candidate key functions, Describe the candidate key functions ...

Describe the candidate key functions ? Candidate Key and Alternate Key: In some instances, an entity will have more than one attribute which can serve as a primary key. Any key

3NF Normalization, Need 2 projects completed in 3NF format.

Need 2 projects completed in 3NF format.

What is relationship, What is relationship? Give examples A relationshi...

What is relationship? Give examples A relationship is an association between several entities. Example: A depositor relationship associates a customer with every account tha

Explain group by clause in sql, Explain group By clause in SQL? Group B...

Explain group By clause in SQL? Group By clause in SQL: The GROUP BY clause can be used in a SELECT statement to collect data across multiple records and group the results thro

Compare the nested-loop join and block-nested loop join, Compare the Nested...

Compare the Nested-loop join and block-nested loop join Ans: Nested  loop join - It is costly as worst case cost, no. of block accesses needed is n r * b s + b r   where b

Calculate the record size r in bytes, An employee record has the following ...

An employee record has the following structure struct employee { int eno; char name[22]; float salary; char dept[10];}; (i) Calculate the record size R in bytes.

Develop a database design , A practice called Perfect Pets provides private...

A practice called Perfect Pets provides private health care for domestic pets throughout America. This service is provided through various clinics located in the main cities of Ame

What are the comparison operator in sql, What are the comparison operator i...

What are the comparison operator in SQL?  Comparison operator in SQL are =, LIKE and BETWEEN

Describe the types of attributes, Describe the types of attributes? Ty...

Describe the types of attributes? Types of attributes: An attribute's category determines the type of values that are permitted in the attribute. For instance, the value vers

Describe deductive databases and relational databases, Problem : (b) A ...

Problem : (b) A deductive database system is essentially the outcome of applying mathematics logic to database management, where logic is used for both data representation and

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