ACID

ACID is an acronym that stands for Atomicity, Consistency, Isolation, and Durability.

It is a set of properties that guarantee the reliability of transactions in a database system.

These properties ensure that database transactions are processed reliably even in the presence of failures.

  1. Atomicity: Atomicity ensures that either all operations of a transaction are successfully completed and committed, or none of them are. This means that if any part of a transaction fails, the entire transaction is rolled back, and the database is left unchanged. Atomicity ensures that the database remains in a consistent state, even in the event of failures or interruptions.

  2. Consistency: Consistency ensures that the database remains in a valid state before and after the execution of a transaction. It guarantees that all constraints, rules, and relationships defined in the database schema are satisfied at the end of each transaction. Consistency prevents the database from entering an invalid state, ensuring that data integrity is maintained.

  3. Isolation: Isolation ensures that the execution of multiple transactions concurrently does not interfere with each other. Each transaction should operate independently of other transactions, as if it were the only transaction executing on the database. Isolation prevents concurrency-related issues such as dirty reads, non-repeatable reads, and phantom reads. Different isolation levels, such as Read Uncommitted, Read Committed, Repeatable Read, and Serializable, provide varying degrees of isolation.

  4. Durability: Durability ensures that once a transaction is committed, its effects persist even in the event of system failures. This means that changes made by a committed transaction are permanently stored in the database and cannot be lost, even if the system crashes or restarts. Durability is typically achieved through mechanisms such as write-ahead logging and transaction checkpoints.

In software development, adherence to ACID properties is essential for building reliable and robust database systems. ACID transactions provide a framework for ensuring data consistency, integrity, and reliability, which are critical requirements for many applications, especially those handling sensitive or mission-critical data.

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