Decode ACID Properties : Basics and Benefits


What is ACID and Why is it Important for Database Transactions?

Database transactions are operations that modify the data stored in a database i.e. CRUD. Transactions are required for the reliability, consistency and accuracy of the data in the database. But, not all transactions are created equal. Some transactions may have different requirements and expectations than others, depending on the nature and purpose of the data and the application.

One way to classify and evaluate transactions is by using the ACID model. ACID stands for Atomicity, Consistency, Isolation and Durability. These are four properties that guarantee that a transaction is executed in a safe and correct manner, regardless of any errors, failures or concurrency issues that may occur. We will try to explain what each of these properties means, why they are important, and how they can be achieved in a database system.


Atomicity means that a transaction is either executed completely or not at all. There is no state in between. You don't see a partial completion of a transaction. For example, if you want to transfer money from one bank account to another, expectation is, either both accounts are updated with the correct amounts, or none of them are changed at all. You don't want to end up with a situation where the money is deducted from one account but not added to the other, or vice versa.

Atomicity prevents partial updates or data loss in case of failures or errors. If something goes wrong during the execution of a transaction, such as a power outage, a network failure, or an application bug, the database system should be able to detect it and roll back the transaction to its original state before it started. This way, the database remains consistent and no data is corrupted or lost.

To achieve atomicity, database systems use various techniques, such as logging, locking, checkpoints and rollback segments. These techniques allow the database system to keep track of the changes made by a transaction, lock the resources involved in the transaction, save the state of the database before the transaction begins, and undo the changes if the transaction fails.


Consistency means that a transaction preserves the validity and integrity of the database state. A database has certain rules and constraints that define what constitutes a valid state. For example, a database may have primary keys that uniquely identify each record, foreign keys that link records from different tables, check constraints that limit the range or format of values in a column, or business rules that enforce some logic or calculation on the data.

Consistency prevents violations of constraints, rules or business logic in the database. If a transaction tries to insert, update or delete data that would break any of these rules or constraints, the transaction should fail and abort. The database should not allow any invalid or inconsistent data to be stored or retrieved.

To achieve consistency, database systems use various techniques, such as validation checks, triggers and stored procedures. These techniques allow the database system to verify and enforce the rules and constraints on the data before and after a transaction is executed. 


Isolation means that concurrent transactions do not interfere with each other. Transactions are concurrent when they are executed at or near the same time by different users or applications. For example, if two customers try to book the same flight seat or hotel room at the same time, they are executing concurrent transactions.

Isolation prevents anomalies such as dirty reads, non-repeatable reads or phantom reads in the database. A dirty read occurs when a transaction reads data that has been modified but not committed by another transaction. A non-repeatable read occurs when a transaction reads the same data twice but gets different results because another transaction has modified and committed the data in between. A phantom read occurs when a transaction reads a set of data that matches some criteria but gets different results because another transaction has inserted or deleted some records that match or do not match the criteria in between.

To achieve isolation, database systems use various techniques, such as locking, timestamps and multi-version concurrency control (MVCC). These techniques allow the database system to control and coordinate the access and modification of data by concurrent transactions. 


Durability means that the effects of a committed transaction are permanent and persistent in the database. A committed transaction is one that has been successfully executed and verified by the database system. Once a transaction is committed, it should not be reversed or undone by any subsequent event.

Durability prevents data loss or corruption in case of power failures, system crashes or restarts. If any of these events happen after a transaction is committed, the database system should be able to recover and restore the data to its latest committed state.

To achieve durability, database systems use various techniques, such as write-ahead logging (WAL), checkpoints and backups. These techniques allow the database system to record and save the changes made by a transaction to persistent storage devices (such as disks), periodically synchronize the data in memory and on disk, and create copies of the data for recovery purposes.


ACID properties are essential for ensuring the reliability, consistency and accuracy of database transactions. They provide a framework for designing and evaluating database systems and applications that deal with sensitive and critical data. By following the ACID model, database systems and applications can avoid many common problems and errors that may compromise the quality and integrity of the data.

Scalable Alternative to ACID

Decode Design Principles


SOLIDify Your Code: Mastering Design Principles for Impenetrable Software

I. Introduction

Software design principles are crucial for developing robust and maintainable code. By understanding and implementing design principles, developers can create software that is resilient to changes, easy to understand, and scalable. In this article, we will explore the benefits of writing solid code and delve into the SOLID principles – a set of five design principles that provide a foundation for building high-quality software.

II. Understanding the SOLID Principles

A. The Single Responsibility Principle (SRP)

The Single Responsibility Principle (SRP) states that a class should have only one responsibility. By adhering to this principle, we can ensure that classes focus on a single purpose, making them easier to understand, test, and maintain. For example, if we have a class responsible for handling user authentication, it should not also be responsible for sending emails. This separation of concerns enhances code readability and minimizes the impact of changes.

B. The Open/Closed Principle (OCP)

The Open/Closed Principle (OCP) promotes code extensibility by stating that classes should be open for extension but closed for modification. This principle encourages us to design our software in a way that allows new functionality to be added without needing to modify existing code. By leveraging techniques such as inheritance, composition, and interfaces, we can achieve code that is adaptable and easily extended, without breaking existing functionality.

C. The Liskov Substitution Principle (LSP)

The Liskov Substitution Principle (LSP) focuses on the behavior of subtypes and their relationship with the base type. It states that subtypes must be substitutable for their base types without changing correctness. In other words, any instance of a base class should be replaceable with an instance of its derived class without affecting the program's behavior. Violating this principle can lead to unexpected issues and hinder code reuse.

D. The Interface Segregation Principle (ISP)

The Interface Segregation Principle (ISP) emphasizes the importance of segregating interfaces to avoid classes from being forced to depend on methods they do not use. By creating smaller and more cohesive interfaces, we can ensure that classes only depend on the methods they need to fulfill their responsibilities. This principle leads to code that is more focused, easier to maintain, and less prone to interface pollution.

E. The Dependency Inversion Principle (DIP)

The Dependency Inversion Principle (DIP) guides the decoupling of modules by inverting the traditional dependency flow. It suggests that high-level modules should not depend on low-level modules directly; instead, both should depend on abstractions. This principle promotes loose coupling, allowing modules to be easily replaced and tested. One popular technique for implementing DIP is through dependency injection, which allows dependencies to be injected into classes rather than being hardcoded.

III. Applying SOLID Principles in Practice

A. SOLID Principles in Object-Oriented Design

SOLID principles have a significant impact on object-oriented programming (OOP) design. By adhering to these principles, developers can create classes that are focused, modular, and loosely coupled. This, in turn, leads to code that is more maintainable, testable, and adaptable. When designing classes, it is important to consider principles such as SRP, OCP, LSP, ISP, and DIP to ensure the creation of high-quality and extensible software.

B. SOLID Principles in Functional Programming

Although SOLID principles were initially tailored for OOP, they can also be applied to functional programming (FP) paradigms. By combining SOLID principles with concepts such as immutability and pure functions, developers can create functional code that is flexible and easy to reason about. SOLID principles in FP emphasize the separation of concerns, immutability, and composability, resulting in highly modular and scalable code.

C. SOLID Principles in Software Architecture

Scaling SOLID principles to enterprise-level applications requires careful consideration of software architecture. By designing modular and maintainable architectures that adhere to SOLID principles, organizations can improve the agility and scalability of their software. These principles promote loose coupling, separation of concerns, and abstraction, allowing for easy maintenance, component reusability, and easier adaptation to changing business requirements.

D. SOLID Principles in Test-Driven Development (TDD)

Incorporating SOLID principles in Test-Driven Development (TDD) can greatly enhance the effectiveness and reliability of tests. SOLID code tends to be more testable due to its focused responsibilities, loose coupling, and modularity. By designing code with testability in mind, developers can improve the reliability and maintainability of their tests while fostering a culture of testing and continuous integration.

IV. Effectively Refactoring Legacy Code

A. Identifying Signs of Poor Design

Legacy code is often riddled with poor design choices that can impede productivity and maintainability. Identifying signs of poor design, such as tight coupling, god classes, and high cyclomatic complexity, is crucial for effective refactoring. By applying SOLID principles, developers can address code smells and improve the overall quality of the codebase.

B. Strategies for Gradual Refactoring

Refactoring a large legacy codebase can be a daunting task. To manage the process effectively, developers can adopt step-by-step approaches that slowly introduce SOLID principles into the codebase. By prioritizing areas for improvement, developers can gradually refactor the codebase, ensuring that each refactoring step is performed safely and that code functionality is maintained.

C. Safely Introducing SOLID Principles

Introducing SOLID principles into an existing codebase carries some risks. It is important to manage these risks effectively to minimize downtime and mitigate errors. Techniques such as using version control systems, writing comprehensive tests, and performing iterative refactoring can help ensure a smooth transition to SOLID code.

V. Benefits and Challenges of SOLID Code

A. Benefits of Writing SOLID Code

Writing code that adheres to SOLID principles offers numerous advantages. SOLID code is more readable and maintainable, allowing for easier collaboration among team members. The use of SOLID principles promotes scalability and extensibility, making it easier to add new features and accommodate changes. Furthermore, SOLID code instills confidence in the software's reliability and reduces the likelihood of regressions.

B. Challenges and Pitfalls of Implementing SOLID Principles

While implementing SOLID principles brings numerous benefits, there are also challenges to consider. Common obstacles include misconceptions surrounding SOLID principles, resistance to change, and balancing principles with practical considerations. By recognizing and addressing these challenges, developers can overcome them and reap the full benefits of SOLID code.

VI. Common Mistakes and Misconceptions about Java Design Principles

While Java design principles offer numerous benefits, there are some common misconceptions and mistakes that developers should be aware of.

Misunderstanding the Liskov Substitution Principle

The Liskov Substitution Principle can be challenging to comprehend fully. It requires a deep understanding of inheritance, polymorphism, and the relationship between base and derived classes. It is crucial to grasp the essence of LSP to avoid any unexpected behaviors and ensure the correct usage of inheritance in your code.

Overusing the Interface Segregation Principle

Although the Interface Segregation Principle encourages the creation of more fine-grained interfaces, it is essential to strike a balance. Overusing ISP can lead to an excessive number of interfaces, resulting in code that is hard to understand, maintain, and implement. It's crucial to find the right level of granularity and consider the practicality and readability of the code

VII. Conclusion

In conclusion, mastering the SOLID principles is essential for building impenetrable software. By understanding and applying these principles, developers can create code that is robust, scalable, and maintainable. By adopting SOLID principles, teams can work collaboratively, write clean code, and gain confidence in their software's reliability and adaptability.

VIII. FAQs (Frequently Asked Questions)

1.     What are the SOLID principles in software development?

·         The SOLID principles are a set of design principles consisting of the Single Responsibility Principle (SRP), Open/Closed Principle (OCP), Liskov Substitution Principle (LSP), Interface Segregation Principle (ISP), and Dependency Inversion Principle (DIP). These principles guide the creation of high-quality and maintainable software.

1.     How do SOLID principles help in writing better code?

·         SOLID principles enhance code quality by promoting modularity, testability, and maintainability. They reduce coupling between components and help manage complexity, making code easier to extend and adapt to changing requirements.

1.     Can SOLID principles be applied to any programming language?

·         Yes, SOLID principles can be applied to any programming language or paradigm. While they were initially formulated for object-oriented programming, the principles can also be adapted to functional programming or other paradigms.

1.     What are some recommended resources for learning more about SOLID principles?

·         Some recommended resources for learning more about SOLID principles include the book "Clean Code: A Handbook of Agile Software Craftsmanship" by Robert C. Martin, online tutorials, and articles from reputable software development websites and blogs.

1.     Is it necessary to strictly adhere to SOLID principles in every scenario?

·         While adhering to SOLID principles is generally beneficial, there may be scenarios where strict adherence is not practical. It is important to strike a balance between principles and practical considerations, taking into account factors such as project constraints, trade-offs, and team dynamics.

1.     How long does it take to see the benefits of refactoring code using SOLID principles?

·         The time it takes to see the benefits of refactoring code using SOLID principles depends on various factors, including the size and complexity of the codebase, the level of technical debt, and the team's expertise. However, even incremental improvements can yield immediate benefits, such as improved code readability and maintainability.