For Database Systems – the Consistency in ACID properties is part of the acronym:
- A – Atomicity
- C – Consistency
- I – Isolation
- D – Durability
For NoSQL Systems, the Consistency in the CAP Theorem is part of the acronym:
- C – Consistency
- A – Availability
- P – Partition tolerance
The meanings are slightly different. In short:
- Consistency in ACID means that no dataset may be an invalid state or represents data which are semantically invalid after a transaction is committed (“internal consistency”).
- Consistency in CAP means that after a transaction is executed this dataset must be updated in all replications too.