Databases – What is ACID?

Acronyms, Abbreviations, Terms, And Definitions, What is ACID?

Acronyms, Abbreviations, Terms, And Definitions

What does ACID mean in database technologies?

  • Concerning databases, the acronym ACID means: Atomicity, Consistency, Isolation, and Durability.

Why is ACID important?

  • Atomicity, Consistency, Isolation, and Durability (ACID) are import to database, because ACID is a set of properties that guarantee that database transactions are processed reliably.

Where is the ACID Concept described?

  • Originally described by Theo Haerder and Andreas Reuter, 1983, in ‘Principles of Transaction-Oriented Database Recovery’, the ACID concept has been codified in ISO/IEC 10026-1:1992, Section 4

What is Atomicity?

  • Atomicity ensures that only two possible results from transactions, which are changing multiple data sets:
  • either the entire transaction completes successfully and is committed as a work unit
  • or, if part of the transaction fails, all transaction data can be rolled back to databases previously unchanged dataset

What is Consistency?

  • To provide consistency a transaction either creates a new valid data state or, if any failure occurs, returns all data to its state, which existed before the transaction started. Also, if a transaction is successful, then all changes to the system will have been properly completed, the data saved, and the system is in a valid state.

What is Isolation?

  • Isolation keeps each transaction’s view of database consistent while that transaction is running, regardless of any changes that are performed by other transactions. Thus, allowing each transaction to operate, as if it were the only transaction.

What is Durability?

  • Durability ensures that the database will keep track of pending changes in such a way that the state of the database is not affected, if a transaction processing is interrupted. When restarted, databases must return to a consistent state providing all previously saved/committed transaction data

 

Related References

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What is DCL?

SQL (Structured Query Language)

SQL (Structured Query Language)

What is DCL (Data Control Language)?

Data control language (DCL) is anything that is used for administrating access (permissions/security) to database content.  The main DCL commands are:

  • Grant
  • Revoke

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