What are the features of HASH

This article mainly shows you "what are the characteristics of HASH", the content is easy to understand, clear, hope to help you solve your doubts, the following let the editor lead you to study and learn "what are the characteristics of HASH" this article?

Hash satisfaction characteristic

Balance: balance means that the results of the hash can be distributed to all buffers as much as possible, so that all buffer space can be utilized.

The "virtual node" is introduced: "virtual node" is a copy of the actual node in the hash space. One actual node corresponds to several "virtual nodes", and this corresponding number also becomes the "copy number". The "virtual nodes" are arranged with hash values in the hash space.

Monotonicity: monotonicity means that if something has been hashed into the corresponding buffer, a new buffer is added to the system. The result of the hash should ensure that the original allocated content can be mapped to the new buffer and not to other buffers in the old buffer set.

Dispersibility

Load

Annular Hash space

According to the commonly used hash algorithm, the corresponding key is hashed into a space with 2 ^ 32 buckets, that is, 0 ~ (2 ^ 32)-1. Now we can connect these numbers end to end and imagine them as a closed ring.

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