Transaction Processing Concept

 Transaction

o The transaction is a set of logically related operation. It 

contains a group of tasks.

o A transaction is an action or series of actions. It is 

performed by a single user to perform operations for 

accessing the contents of the database.

Example: Suppose an employee of bank transfers Rs 800 from 

X's account to Y's account. This small transaction contains several 

low-level tasks:

X's Account

1. Open_Account(X) 

2. Old_Balance = X.balance 

3. New_Balance == Old_Balance - 800 

4. X.balance = New_Balance 

5. Close_Account(X) 

Y's Account

1. Open_Account(Y) 

2. Old_Balance = Y.balance 

3. New_Balance = Old_Balance + 800 

4. Y.balance = New_Balance 

5. Close_Account(Y) 

Operations of Transaction:

Following are the main operations of transaction:

Read(X): Read operation is used to read the value of X from the 

database and stores it in a buffer in main memory.

Write(X): Write operation is used to write the value back to the 

database from the buffer.

Let's take an example to debit transaction from an account which 

consists of following operations:

1. 1. R(X); 

2. 2. X = X - 500; 

3. 3. W(X); 

Let's assume the value of X before starting of the transaction is 

4000.

o The first operation reads X's value from database and 

stores it in a buffer.

o The second operation will decrease the value of X by 

500. So buffer will contain 3500.

o The third operation will write the buffer's value to the 

database. So X's final value will be 3500.

But it may be possible that because of the failure of hardware, 

software or power, etc. that transaction may fail before finished 

all the operations in the set.

For example: If in the above transaction, the debit transaction 

fails after executing operation 2 then X's value will remain 4000 

in the database which is not acceptable by the bank.

To solve this problem, we have two important operations:

Commit: It is used to save the work done permanently.

Rollback: It is used to undo the work done.

Transaction property

The transaction has the four properties. These are used to 

maintain consistency in a database, before and after the 

transaction.

Property of Transaction

1. Atomicity

2. Consistency

3. Isolation

4. Durability

Atomicity

o It states that all operations of the transaction take place at 

once if not, the transaction is aborted.

o There is no midway, i.e., the transaction cannot occur 

partially. Each transaction is treated as one unit and 

either run to completion or is not executed at all.

Atomicity involves the following two operations:

Abort: If a transaction aborts then all the changes made are not 

visible.

Comments

Post a Comment

Popular posts from this blog

Early Disease Detection with Machine Learning and Deep Learning

 In today’s healthcare landscape, early detection of diseases is a game-changer. Identifying health conditions early not only improves patient outcomes but also reduces treatment costs. Machine learning (ML) and deep learning (DL) are revolutionizing this process, enabling healthcare systems to detect diseases with unprecedented accuracy and speed. Early detection of diseases like cancer, diabetes, and cardiovascular conditions can significantly improve survival rates. However, traditional diagnostic methods often rely on time-consuming tests and subjective interpretation, leading to delays or errors. Enter machine learning and deep learning: technologies that learn from vast datasets to identify patterns invisible to the human eye. Cancer Detection: DL algorithms have achieved radiologist-level accuracy in detecting breast cancer from mammograms. COVID-19 Diagnosis: AI models analyze chest CT scans to identify COVID-19 with high precision. Alzheimer’s Detection: ML models analy...
Read more

Computer Forensics: An Overview

  Key Aspects of Computer Forensics 1. Phases of Computer Forensic Investigation A typical forensic investigation follows a structured process: a) Identification Detect and recognize potential digital evidence sources (e.g., computers, mobile devices, cloud storage). Identify key stakeholders, such as law enforcement agencies or corporate security teams. b) Preservation Secure digital evidence without tampering. Use write-blocking tools to prevent data alteration. Create forensic copies (bit-by-bit images) of storage devices. c) Analysis Examine data for traces of malicious activity, deleted files, hidden data, or encrypted content. Use forensic tools like EnCase, FTK, Autopsy, X-Ways Forensics to extract evidence. Reconstruct events using system logs, timestamps, and metadata. d) Documentation Record all findings systematically. Maintain chain-of-custody records to ensure admissibility in court. Generate forensic reports detailing the investigation process and conclusions. e) Pre...
Read more