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See also ACID (Atomicity, Consistency, Isolation, Durability)

Atomicity is one of the fundamental properties of a database transaction, ensuring that all operations within the transaction are executed as a single, indivisible unit. In the context of database management systems (DBMS), atomicity guarantees that either all operations in a transaction are completed successfully and the transaction is committed, or none of the operations are applied, and the transaction is rolled back to its initial state. This property prevents partial execution of transactions, maintaining data consistency and integrity. Atomicity is essential for ensuring that database transactions are reliable and that the database remains in a consistent state, even in the event of failures or errors during transaction processing. s://en.wikipedia.org/wiki/Atomicity_(database_systems)

In database systems, atomicity is one of the ACID (Atomicity, Consistency (database systems) | Consistency, Isolation (database systems) | Isolation, Durability (database systems) | Durability) database transaction | transaction properties. An atomic transaction is an indivisible and Irreducibility | irreducible series of database operations such that either all occur, or nothing occurs.

Snippet from Wikipedia: Atomicity (database systems)

In database systems, atomicity (; from Ancient Greek: ἄτομος, romanized: átomos, lit. 'undividable') is one of the ACID (Atomicity, Consistency, Isolation, Durability) transaction properties. An atomic transaction is an indivisible and irreducible series of database operations such that either all occur, or none occur. A guarantee of atomicity prevents partial database updates from occurring, because they can cause greater problems than rejecting the whole series outright. As a consequence, the transaction cannot be observed to be in progress by another database client. At one moment in time, it has not yet happened, and at the next it has already occurred in whole (or nothing happened if the transaction was cancelled in progress).

An example of transaction atomicity could be a digital monetary transfer from bank account A to account B. It consists of two operations, debiting the money from account A and crediting it to account B. Performing both of these operations inside of an atomic transaction ensures that the database remains in a consistent state, if either operation fails there will not be any unaccountable credits or debits affecting either account.

The same term is also used in the definition of First normal form in database systems, where it instead refers to the concept that the values for fields may not consist of multiple smaller values to be decomposed, such as a string into which multiple names, numbers, dates, or other types may be packed.

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• Atomicity (database systems), a property of database transactions which are guaranteed to either completely occur, or have no effects
• Atomicity (programming), an operation appears to occur at a single instant between its invocation and its response
• Atomicity, a property of an S-expression, in a symbolic language like Lisp

Atomicity is one of the fundamental properties of ACID (Atomicity, Consistency, Isolation, Durability) transactions in database systems. It ensures that a transaction is treated as a single, indivisible unit of work. This means that either all operations within the transaction are completed successfully, or none of them are applied. Atomicity is crucial for maintaining data integrity and consistency in database systems.

In the context of database transactions, atomicity implies that a transaction cannot be divided into smaller parts. Each transaction must either be fully completed or fully rolled back. This all-or-nothing approach prevents partial updates that could lead to inconsistent or corrupted data. For example, if a transaction involves transferring funds from one account to another, atomicity ensures that both the debit and credit operations are completed together, or neither operation is applied.

• Transaction Logs: To support atomicity, databases use transaction logs to record each operation performed during a transaction. If a transaction fails or is interrupted, the system can use these logs to roll back changes and restore the database to its previous state.
• Commit and Rollback: Atomicity is enforced through commit and rollback operations. A commit finalizes all changes made during the transaction, making them permanent. Conversely, a rollback undoes all changes if an error or issue occurs, reverting the database to its state before the transaction began.

• Failure Recovery: In the event of a system failure, atomicity ensures that the database can recover to a consistent state. The system uses transaction logs to identify incomplete transactions and roll them back, preventing partial updates that could compromise data integrity.
• Error Handling: During transaction execution, if an error occurs, the database management system (DBMS) automatically initiates a rollback to maintain atomicity. This prevents the application of partial changes and ensures that the database remains consistent.

Atomicity becomes more complex in Distributed Systems, where transactions span multiple databases or services. In such cases, maintaining atomicity across distributed components requires additional protocols and mechanisms:

• Two-Phase Commit (2PC) Protocol: This protocol coordinates transactions across multiple systems by having a preparatory phase followed by a commit phase. All participating systems must agree to commit the transaction or all must roll back to ensure atomicity.
• Distributed Transaction Coordinators: These coordinators manage and ensure the atomicity of transactions that involve multiple databases or services. They oversee the transaction process and handle communication and coordination between distributed components.

• Performance Impact: Enforcing atomicity, especially in high-concurrency environments, can impact performance. The need for logging, rollback mechanisms, and coordination among distributed systems may introduce latency.
• Deadlocks: Ensuring atomicity can lead to deadlocks, where two or more transactions are waiting for each other to release resources. Deadlock detection and resolution strategies are necessary to address this issue.

• Blockchain Technology: Blockchain provides an alternative approach to transaction management by using decentralized ledgers and consensus algorithms to achieve atomicity without a central authority. This technology offers transparency and immutability in transaction processing.
• In-Memory Databases: In-memory databases that store data in RAM rather than on disk can enhance performance while maintaining atomicity. These databases are increasingly used in applications requiring high-speed transactions and real-time data access.

• https://en.wikipedia.org/wiki/Atomicity_(database_systems)
• https://www.oracle.com/database/what-is-database-transaction/#Atomicity
• https://www.ibm.com/docs/en/db2/11.1?topic=transactions
• https://www.microsoft.com/en-us/sql-server/sql-server-2019

Snippet from Wikipedia: Atomicity

Atomicity may refer to:

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