在MySQL中存储SHA1哈希值 [英] Storing SHA1 hash values in MySQL

问题描述

我有一个简单的问题，当我想把一个SHA1哈希的结果存储在一个MySQL数据库中时：

I have a simple question which occured when I wanted to store the result of a SHA1 hash in a MySQL database:

/ em>字段在其中存储哈希的结果？

How long should the VARCHAR field be in which I store the hash's result?

推荐答案

我会使用 VARCHAR 用于可变长度数据，但不具有固定长度数据。因为SHA-1值总是 160位，所以 VARCHAR 只会浪费固定长度字段长度的附加字节。

I would use VARCHAR for variable length data, but not with fixed length data. Because a SHA-1 value is always 160 bit long, the VARCHAR would just waste an additional byte for the length of the fixed-length field.

我也不会将 SHA1 正在返回。因为它每个字符只使用4位，因此需要160/4 = 40个字符。但是如果你每个字符使用8位，你只需要一个160/8 = 20个字符的长字段。

And I also wouldn’t store the value the SHA1 is returning. Because it uses just 4 bit per character and thus would need 160/4 = 40 characters. But if you use 8 bit per character, you would only need a 160/8 = 20 character long field.

所以我建议你使用 BINARY（20） 和 UNHEX 函数将 SHA1 值转换为二进制。

So I recommend you to use BINARY(20) and the UNHEX function to convert the SHA1 value to binary.

我比较了 BINARY（20）和 CHAR（40）。

CREATE TABLE `binary` (
    `id` int unsigned auto_increment primary key,
    `password` binary(20) not null
);
CREATE TABLE `char` (
    `id` int unsigned auto_increment primary key,
    `password` char(40) not null
);

拥有百万条记录 binary（20）需要44.56M，而 char（40）需要64.57M。
InnoDB 引擎。

With million of records binary(20) takes 44.56M, while char(40) takes 64.57M. InnoDB engine.

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