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Command: Exists

Checks if a key exists in the persistent storage. If the key does not exist false is returned.

exists `config/limits/max-connections`
r- not exists 9ms

set `config/limits/max-connections` 1000
r0 set 11ms

exists `config/limits/max-connections`
r0 exists 8ms

exists is useful for checking whether a key is present in the key/value store without incurring the cost of returning the full byte stream of the associated value to the client.

This makes it an efficient way to perform presence checks, especially when working with large values or when you only need to know if a key exists before taking further action.

Example:

let exists_key = exists "user:123:profile"
if exists_key then
  return "User found"
else
  return "User not found"
end

Exists As Of Timestamp​

exists also supports historical snapshot reads:

exists `config/limits/max-connections` as of 1718392012345

This checks whether the key existed at that snapshot time, not whether it exists now.