Version Addressable

RedisMemo is a version-addressable caching system. But what exactly is “version-addressable”?

Version Addressable is a made-up term, derived from the term “content-addressable”.

https://en.wikipedia.org/wiki/Content-addressable_storage

Content-addressable storage, also referred to as content-addressed storage or abbreviated CAS, is a way to store information so it can be retrieved based on its content, not its location.

Similar to a content-addressable storage system, RedisMemo store information on Redis so it can be retrieved based on its version, not its location (aka its raw cache key).

In order to find a cached result, RedisMemo makes an additional roundtrip to Redis, retrieves the latest versions of its dependencies, then calculates a cache key that represents the latest version of the cached result (a checksum of the dependencies versions).

• If any of the dependencies versions have been changed, the actual cache key (checksum of the dependencies version) would differ, and result in a cache miss.
• If the latest version of the cached result is not yet available (cache miss), then RedisMemo executes the original code path and fills the cached result for that particular version.