Page 94 - CITS - Computer Software Application -TT

COMPUTER SOFTWARE APPLICATION - CITS

Some important points

Property Responsibility for maintaining properties

Atomicity Transaction Manager

Consistency Application programmer

Isolation Concurrency Control Manager

Durability Recovery Manager

The ACID properties, in totality, provide a mechanism to ensure the correctness and consistency of a database in
a way such that each transaction is a group of operations that acts as a single unit, produces consistent results,
acts in isolation from other operations, and updates that it makes are durably stored.
ACID properties are the four key characteristics that define the reliability and consistency of a transaction in a
Database Management System (DBMS). The acronym ACID stands for Atomicity, Consistency, Isolation, and
Durability. Here is a brief description of each of these properties:

1 Atomicity: Atomicity ensures that a transaction is treated as a single, indivisible unit of work. Either all the
operations within the transaction are completed successfully, or none of them are. If any part of the transaction
fails, the entire transaction is rolled back to its original state, ensuring data consistency and integrity.
2 Consistency: Consistency ensures that a transaction takes the database from one consistent state to another
consistent state. The database is in a consistent state both before and after the transaction is executed.
Constraints, such as unique keys and foreign keys, must be maintained to ensure data consistency.
3 Isolation: Isolation ensures that multiple transactions can execute concurrently without interfering with each
other. Each transaction must be isolated from other transactions until it is completed. This isolation prevents
dirty reads, non-repeatable reads, and phantom reads.
4 Durability: Durability ensures that once a transaction is committed, its changes are permanent and will survive
any subsequent system failures. The transaction’s changes are saved to the database permanently, and even
if the system crashes, the changes remain intact and can be recovered.
Overall, ACID properties provide a framework for ensuring data consistency, integrity, and reliability in DBMS.
They ensure that transactions are executed in a reliable and consistent manner, even in the presence of system
failures, network issues, or other problems. These properties make DBMS a reliable and efficient tool for managing
data in modern organizations.
Advantages of ACID Properties in DBMS
1 Data Consistency: ACID properties ensure that the data remains consistent and accurate after any transaction
execution.
2 Data Integrity: ACID properties maintain the integrity of the data by ensuring that any changes to the database
are permanent and cannot be lost.

3 Concurrency Control: ACID properties help to manage multiple transactions occurring concurrently by
preventing interference between them.
4 Recovery: ACID properties ensure that in case of any failure or crash, the system can recover the data up to
the point of failure or crash.

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CITS : IT&ITES - Computer software application - Lesson 18 - 36