RENAMENX

Introduction and Use Case(s)

The RENAMENX command in Redis is used to rename a key only if the new key does not already exist. This ensures that you do not accidentally overwrite an existing key. Typical use cases include safely renaming keys in situations where key conflicts need to be avoided.

Syntax

  1. RENAMENX oldkey newkey

Parameter Explanations

  • oldkey: The current key you want to rename.
  • newkey: The new name for the key, which must not already exist in the database.

Return Values

RENAMENX returns an integer:

  • 1: If the key was successfully renamed.
  • 0: If the new key already exists and the rename operation was not performed.

Code Examples

  1. dragonfly> SET mykey "value"
  2. OK
  3. dragonfly> RENAMENX mykey mynewkey
  4. (integer) 1
  5. dragonfly> GET mynewkey
  6. "value"
  7. dragonfly> SET anotherkey "anothervalue"
  8. OK
  9. dragonfly> RENAMENX mynewkey anotherkey
  10. (integer) 0
  11. dragonfly> GET mynewkey
  12. "value"
  13. dragonfly> GET anotherkey
  14. "anothervalue"

Best Practices

  • Always ensure that the newkey you are renaming to does not exist to avoid unexpected behaviors.
  • Make use of EXISTS newkey before calling RENAMENX to verify the key’s non-existence if needed.

Common Mistakes

  • Attempting to rename a key to an existing key without checking: This will cause the operation to fail (0 as the return value).
  • Confusing RENAMENX with RENAME, which will overwrite the new key regardless of its existence.

FAQs

Can I use RENAMENX to swap keys?

No, RENAMENX does not support swapping keys. It only renames a key if the new key does not exist.

What happens if the old key does not exist?

If the oldkey does not exist, RENAMENX behaves like other commands operating on non-existent keys and returns 0. No key is created or modified in this case.