Glossary

The terms the KV Store documentation uses in its own way, each defined once and linked to the page that carries it in full.

Term	Definition
`Azion.KV`	The runtime global that reaches KV Store from inside a function. Its constructor is private, so the only way to a client is the awaited `Azion.KV.open`, and there is no import line to write. KV client documents every method it carries.
`Azion.KV.open`	The static method that opens a namespace by name and returns the client for it. It is asynchronous, and it is the only entry point to the data. KV client carries its signature.
`cacheTtl`	The option a single-key `get` or `getWithMetadata` accepts to set how many seconds the result stays cached where the function that read it ran. Best practices says when raising it helps and when it costs you.
cold read	A read whose result is not already cached where the function runs, so KV Store fetches the value before answering. A hot read is one the cache answers. A read of a key that does not exist is cached the same way, so `cacheTtl` governs it too.
default namespace	It does not exist: every client names the namespace it opens, and KV client shows the only form that opens one.
eventual consistency	The consistency model KV Store applies. A write is readable where it was made before it is readable everywhere else, and concurrent writes to one key resolve to the last write. How KV Store works describes what a read can return in between.
`expiration`	The `put` option that expires a key at a Unix timestamp given in seconds. `expirationTtl` expresses the same expiry as a count of seconds instead. KV client documents both.
`expirationTtl`	The `put` option that expires a key after a number of seconds, counted rather than given as a point in time. `expiration` is the same expiry given as a timestamp. KV client documents both.
keys read	The billing meter that counts every key read from KV Store. It is one of three, with keys written and storage, and KV Store limits carries the amount included.
keys written	The billing meter that counts every key a write affects, including a `put` and a `delete`. KV Store limits carries the amount included.
metadata	A serializable value stored beside a key’s value and set through the `put` option of the same name. `getWithMetadata` returns it next to the value, and it is `null` when the key carries none. KV client documents both calls.
multi-key get	A `get` or `getWithMetadata` given an array of keys rather than one. It returns a plain object, accepts only the `text` and `json` return types, and duplicate keys in the array are removed. KV client documents the shape and what an absent key returns.
namespace	An isolated key space, addressed by the name it was created with, which is also its identifier. A namespace is permanent: it cannot be renamed, deactivated, emptied, or deleted on any interface. Namespaces documents its fields and the API that creates it.
Preview	The release stage KV Store ships at. Preview access is granted on request and subject to approval, so an account does not hold it until technical support enables it.
`returnType`	The second argument to `get` and `getWithMetadata`, which decides the form the value comes back in. It defaults to `text`, and KV client lists every value it accepts.
storage	The billing meter for the data your namespaces hold. It is one of three, with keys read and keys written, and KV Store limits carries the amount included.