APPENDAppend bytes to a string value; returns the new length.
| 语法 | APPEND key value |
| 分组 | string |
| 参数个数 | 3 |
| 起始版本 | 1.0.0 |
| 标志 | write |
| 复杂度 | O(1) amortised while the value is <= 64 B; O(N) per call once it exceeds that (the Arc payload is copied out and re-boxed on every append), so building a large string by repeated APPEND is O(N^2) |
| Redis 兼容性 | full |