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ACID

4 properties of the transaction in Database.

Atomic

Every transaction should be done or never do. No mid-state.

Consistency

States should be always OK.

The data should be integrated before transaction start and after transaction end.

Isolation

The transactions should be independence.

Four levels:

  • Read uncommitted: Transaction can read uncommitted data from other transaction.
  • Read committed: Transaction can only read committed data from other transaction.
  • Repeatable read: Same query to same result.
  • Serializable: Same orders of execution of transactions will lead to same result.

Durability

Data never loss.

Example implementation: Write-ahead logging (WAL)

Changelog

Just observe 👀