The ACID properties in SQL database


What is ACID?

If you’ve ever worked with databases, you’ve probably heard of ACID – but what is it, exactly? Well, ACID stands for Atomicity, Consistency, Isolation, and Durability, and it’s a set of properties that are essential for maintaining data integrity.

Essentially, ACID guarantees that database transactions are completed reliably and consistently, and ensures that all writes are done correctly. This is made possible through the use of locks, pessimistic concurrency control mechanisms, and logging, which are implemented by ACID-compliant databases.

So if you want to keep your data secure and ensure that your database functions properly, it’s important to understand and implement the principles of ACID.


Atomicity refers to the treatment of each statement in a transaction (read, write, update, or delete data) as a single unit. Either the entire statement or nothing of it is executed. This property prevents data loss and corruption if, for example, your streaming data source fails in the middle of a stream.


This property states that all transactions are executed in such a way that the database remains in a consistent state while they occur. This means that if some data is being added to or removed from the database during a transaction, any pre-existing constraints imposed by the schema must remain intact during and after each operation for it to be considered successful.


This property implies that concurrent transactions should have an isolated view of all simultaneous operations occurring within their own respective transactions. This means no transaction should interfere with another running simultaneously; instead, each one should operate independently on its own private copy of its required data set throughout the duration of its execution.


This property implies that once a transaction completes or ‘commits’ successfully, permanently changing parts of the database it is supposed to change; its results are stored persistently into the database log file so they cannot be reversed due to unexpected hardware failure or potential system crashes, etc.


In conclusion, ACID greatly increases the reliability of relational databases by helping enforce many important core principles allowing systems like this not only to remain consistent but also reliable over very long periods without fail.