COPYCopy a key's value, and its remaining TTL, to another key.
| Syntax | COPY source destination [REPLACE] |
| Group | generic |
| Arity | -3 |
| Since | 1.0.0 |
| Flags | write |
| Complexity | O(1) same-shard; O(V) across shards, where V is the value copied over the ring |
| Redis compatibility | differs: the DB argument is not accepted — kevy is single-database. A cross-shard copy is not atomic with anything else, but a failure between its two steps leaves both keys untouched |