COPYCopy a key's value, and its remaining TTL, to another key.
| 语法 | COPY source destination [REPLACE] |
| 分组 | generic |
| 参数个数 | -3 |
| 起始版本 | 1.0.0 |
| 标志 | write |
| 复杂度 | O(1) same-shard; O(V) across shards, where V is the value copied over the ring |
| Redis 兼容性 | 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 |