为什么hash槽的大小为16384？-优快云博客

本文链接：https://blog.youkuaiyun.com/Mr_xiayijie/article/details/109729378

这是作者给出的原话：

Normal heartbeat packets carry the full configuration of a node, that can be replaced in an idempotent way with the old in order to update an old config.

正常的心跳包携带节点的完整配置，可以用幂等方式替换旧节点，以便更新旧配置。

This means they contain the slots configuration for a node, in raw form, that uses 2k of space with16k slots, but would use a prohibitive 8k of space using 65k slots.

这意味着它们包含一个节点的插槽配置，在原始形式中，该节点使用2k的空间和16k的插槽，但使用65k的插槽将使用令人望而却步的8k空间。

At the same time it is unlikely that Redis Cluster would scale to more than 1000 mater nodes because of other design tradeoffs.

与此同时，Redis集群不太可能因为其他设计权衡而扩展到超过1000个主节点。

So 16k was in the right range to ensure enough slots per master with a max of 1000 maters, but a small enough number to propagate the slot configuration as a raw bitmap easily.

因此，16k是在合适的范围内，以确保每个主服务器有足够的插槽，最多1000个maters，但这个数字足够小，可以很容易地将插槽配置作为原始位图传播。

Note that in small clusters the bitmap would be hard to compress because when N is small the bitmap would have slots/N bits set that is a large percentage of bits set.

注意，在小型集群中，位图很难压缩，因为当N很小时，位图将设置槽/N位，这是设置的位的很大比例。

Redis集群计算Key的算法：

https://segmentfault.com/a/1190000018094567?utm_source=tag-newest

Key=CRC16(Key)%16384

CRC16(Key)算法有2^16=65536个值，范围0-65535bit之间

也就是根据算法来说：

Key=CRC16(Key)%16384 =>Key=(0-65536)%16384 key的范围0-16383