FLUSHALLDelete every key on every shard.
| 语法 | FLUSHALL |
| 分组 | server |
| 参数个数 | -1 |
| 起始版本 | 1.0.0 |
| 标志 | write |
| 复杂度 | O(S) fan-out; per shard O(N/S) clear plus WATCH invalidation plus a feed-generation bump |
| Redis 兼容性 | differs: ASYNC / SYNC are accepted and ignored (the flush is always synchronous per shard), and it bumps the CDC feed generation, so live FEED cursors get a resync error |