Explanation of BASE terminology
The BASE acronym was defined by Eric Brewer, who is also known for formulating the CAP theorem.
The CAP theorem states that a distributed computer system cannot guarantee all of the following three properties at the same time:
- Consistency
- Availability
- Partition tolerance
A BASE system gives up on consistency.
- Basically available indicates that the system does guarantee availability, in terms of the CAP theorem.
- Soft state indicates that the state of the system may change over time, even without input. This is because of the eventual consistency model.
- Eventual consistency indicates that the system will become consistent over time, given that the system doesn't receive input during that time.
Brewer does admit that the acronym is contrived:
I came up with [the BASE] acronym with my students in their office earlier that year. I agree it is contrived a bit, but so is "ACID" -- much more than people realize, so we figured it was good enough.
It has to do with BASE: the BASE jumper kind is always Basically Available (to new relationships), in a Soft state (none of his relationship last very long) and Eventually consistent (one day he will get married).
Basic Availability: The database appears to work most of the time.
Soft State: Stores don’t have to be write-consistent or mutually consistent all the time.
Eventual consistency: Data should always be consistent, with regards how any number of changes are performed.