Database consistency model
Transaction data consistency in the context of databases refers to the requirement that any database transaction can change data only in allowed ways. Data written to the database will be validated against a set of rules and constraints, and all these checks must always be passed before the data is made available to other users. Currently, there are two popular data consistency models. We'll discuss these models in the following subsections.
ACID data consistency model
When database sizes were measured in megabytes, we could have stringent requirements that enforced strict consistency. Since storage has become exponentially cheaper, databases can be much bigger, often measured in terabytes and even petabytes. For this reason, making databases ACID-compliant for storage reasons is much less prevalent. The ACID model guarantees the following:
- Atomicity: For an operation to be considered atomic, it should ensure that transactions within the operation either...