The Relational Database is built on the principle of ACID (Atomicity, Consistency, Isolation, Durability)

It implies that a truly distributed relational database should have availability, consistency and partition tolerance.

Atomicity

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Atomicity (database systems)

Atomicityrequires that each transaction be "all or nothing": if one part of the transaction fails, then the entire transaction fails, and the database state is left unchanged. An atomic system must guarantee atomicity in each and every situation, including power failures, errors and crashes. To the outside world, a committed transaction appears (by its effects on the database) to be indivisible ("atomic"), and an aborted transaction does not happen.

Consistency

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Consistency (database systems)

The consistency constraints property ensures that any transaction will bring the database from one valid state to another. Any data written to the database must be valid according to all defined rules, including constraints, cascades, triggers, and any combination thereof. This does not guarantee correctness of the transaction in all ways the application programmer might have wanted (that is the responsibility of application-level code), but merely that any programming errors cannot result in the violation of any defined rules.

Isolation

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Isolation (database systems)

Theisolationconcurrency controlproperty ensures that the concurrent execution of transactions results in a system state that would be obtained if transactions were executed sequentially, i.e., one after the other. Providing isolation is the main goal ofrelaxed. Depending on the concurrency control method (i.e., if it uses strict - as opposed to- serializability), the effects of an incomplete transaction might not even be visible to another transaction.

Durability

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Durability (database systems)

Thedurabilitycrashesproperty ensures that once a transaction has been committed, it will remain so, even in the event of power loss,non-volatile memory, or errors. In a relational database, for instance, once a group of SQL statements execute, the results need to be stored permanently (even if the database crashes immediately thereafter). To defend against power loss, transactions (or their effects) must be recorded in a.