GUID/UUID 的 URL 压缩表示?
我需要生成一个 GUID 并通过字符串表示形式保存它。字符串表示形式应尽可能短,因为它将用作已经很长的 URL 字符串的一部分。
现在,我不使用正常的 abcd-efgh-... 表示,而是使用生成的原始字节并对它们进行 Base64 编码,这会导致字符串稍微短一些。
但是有可能让它变得更短吗?
我可以接受失去一定程度的唯一性并保留一个计数器,但是扫描所有现有的密钥不是一个选项。建议?
I need to generate a GUID and save it via a string representation. The string representation should be as short as possible as it will be used as part of an already-long URL string.
Right now, instead of using the normal abcd-efgh-... representation, I use the raw bytes generated and base64-encode them instead, which results in a somewhat shorter string.
But is it possible to make it even shorter?
I'm OK with losing some degree of uniqueness and keeping a counter, but scanning all existing keys is not an option. Suggestions?
如果你对这篇内容有疑问,欢迎到本站社区发帖提问 参与讨论,获取更多帮助,或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱,如果其他用户或者作者回复了您的评论,将不能在第一时间通知您!
发布评论
评论(7)
(很久了,但今天才遇到同样的需求)
UUID 长 128 位,由 32 个十六进制加 4 个连字符表示。
如果我们使用 64 (2^6) 个可打印 ascii 的字典,只需从 32 组 4 位(十六进制长度)转换为 22 组 6 位即可。
这是一个 UUID 缩写。相反,36 个字符您会得到 22 个字符,而不会丢失原始位。
https://gist.github.com/tomlobato/e932818fa7eb989e645f2e64645cf7a5
(long time, but just came into the same need today)
UUIDs are 128bits long, represented by 32 hex plus 4 hyphens.
If we use a dictionary of 64 (2^6) printable ascii`s, it is just a matter of converting from 32 groups of 4 bits (length of a hex) to 22 groups of 6 bits.
Here is a UUID shortner. Instead 36 chars you get 22, without losing the original bits.
https://gist.github.com/tomlobato/e932818fa7eb989e645f2e64645cf7a5
你可以从另一个方向来解决这个问题。生成尽可能短的字符串表示形式并将其映射到 Guid 中。
使用定义的字母表生成密钥,如下所示:
在伪代码中:
如果保持字符串长度 < 16、您可以简单地对结果进行十六进制编码并将其传递给 Guid 构造函数进行解析。
You could approach this from the other direction. Produce the shortest possible string representation and map it into a Guid.
Generate the key using a defined alphabet as below:
In psuedocode:
If you keep the string length < 16, you can simply hex encode the result and pass it to the Guid constructor to parse.
不是完全相同的问题,但非常非常接近 - 我使用了 CRC64、Base64,你得到 11 个字节,CRC64 已经过测试(未经证明),不会在各种字符串上产生重复项。
由于根据定义它是 64 位长,因此您得到的密钥大小只有一半。
要直接回答原始问题 - 您可以对 GUID 的任何表示形式进行 CRC64 编码。
或者只需在业务密钥上运行 CRC64,您将拥有一个 64 位唯一的东西,然后您可以对其进行 base64。
not for exact same problem, but very very close - I have used CRC64, Base64 that and you get 11 bytes, CRC64 has been tested (not proven) to NOT produce duplicates on a wide range of strings.
And since it is 64 bit long by definition - you get the key that is half the size.
To directly answer the original question - you can CRC64 encode any representation of your GUIDs.
Or just run CRC64 on the business key and you will have a 64 bit unique thing that you can then base64.
我使用 Ascii85 编码以 20 个 ASCII 字符将 Guid 写入数据库列。我已经发布了 C# 代码,以防它有用。 URL 编码的特定字符集可能有所不同,但您可以选择适合您的应用程序的字符。它可以在这里找到:将任意 GUID 编码为可读 ASCII (33-127) 的最有效方法是什么?
I used an Ascii85 encoding for writing a Guid to a database column in 20 ASCII characters. I've posted the C# code in case it is useful. The specific character set may be different for a URL encoding, but you can pick whichever characters suit your application. It's available here: What is the most efficient way to encode an arbitrary GUID into readable ASCII (33-127)?
当然,只需使用大于 64 的基数即可。您必须使用自定义字母表对它们进行编码,但您应该能够找到更多“url 安全”的可打印 ASCII 字符。
Base64 使用 8 位对 6 位进行编码,因此 16 字节 GUID 值变为 22 字节编码。您也许可以将其减少一两个字符,但也不能多了。
Sure, just use a base larger than 64. You'll have to encode them using a custom alphabet, but you should be able to find a few more "url-safe" printable ASCII characters.
Base64 encodes 6 bits using 8, so a 16 byte GUID value becomes 22 bytes encoded. You may be able to reduce that by a character or two, but not much more.
我发现这个讨论很有趣:https://www. percona.com/blog/2014/12/19/store-uuid-optimized-way/
基本上,您获取 36 个字符并将它们转换为 16 字节的二进制文件,但首先使用存储过程对三个时间片段进行排序:
I found this discussion interesting: https://www.percona.com/blog/2014/12/19/store-uuid-optimized-way/
Basically you take the 36 characters and turn them into 16 bytes of binary but first sort the three temporal pieces using a stored procedure:
我不确定这是否可行,但您可以将所有生成的 GUID 放入表中,并在 URL 中仅使用表中 GUID 的索引。
您还可以减少 guid 的长度 - 例如,使用 2 个字节表示自 2010 年以来的天数,使用 4 个字节表示自当天开始以来的毫秒数。仅同一毫秒内生成的 2 个 GUID 才会发生冲突。您还可以添加 2 个随机字节,这将使效果更好。
I'm not sure if this is feasible, but you could put all the generated GUIDs in a table and use in the URL only the index of the GUID in the table.
You could also reduce the length of the guid - for example use 2 bytes to indicate the number of days since 2010 for example and 4 bytes for the number of miliseconds since the start of the current day. You will have collisions only for 2 GUIDs generated in the same milisecond. You could also add 2 more random bytes which will make this even better.