查询 - MySQL的按位运算，布隆过滤器

 

查询 - MySQL的按位运算，布隆过滤器

I'd like to implement a bloom filter using MySQL (other a suggested alternative).我想实现一个布隆过滤器使用MySQL（另外一个建议的替代）。

The problem is as follows:问题是如下：

Suppose I have a table that stores 8 bit integers, with these following values:假设我有一个表，用于存储8位整数，以下值：

1: 10011010 2: 00110101 3: 10010100 4: 00100110 5: 00111011 6: 01101010 

I'd like to find all results that are bitwise AND to this:我想找到的所有结果按位与此：

 00011000 

The results should be rows 1 and 5.结果应该是1行和第5行。

However, in my problem, they aren't 8 bit integers, but rather n-bit integers.然而，在我的问题，他们是不是8位整数，而是n位整数。 How do I store this, and how do I query?我如何保存这一点，我怎么查询呢？ Speed is key.速度是关键。

来源：http://stackoverflow.com/questions/360844/mysql-bitwise-operations-bloom-filter

 

• Create a table with int field for value, no need to store numbers as sequence of 0 and 1.创建一个表整型字段值，没有必要存储0和1的序列号。 For you data it will look like this:你的数据，它看起来像这样：

   number 154 53 148 38 59 106 

  and you need to find all entries matching 24.你需要找到所有的匹配项24。

  Then you can run a query like然后，您可以执行这样的查询

   SELECT * FROM test WHERE number & 24 = 24 

  If you want to avoid convertion into 10 base numbers in your application you can hand it over to mysql:如果你想避免皈依为10个基数，在您的应用程序，你可以把它交给到MySQL：

   INSERT INTO test SET number = b'00110101'; 

  and search like this和搜索这样的

   SELECT bin(number) FROM test WHERE number & b'00011000' = b'00011000' 

• Consider not using MySQL for this.考虑不使用MySQL的这个。

  First off, there probably isn't a built-in way for more than 64-bit tables.首先，有可能不是一个内置的方式，超过64位的表。 You'd have to resort to user-defined functions written in C.你不得不求助于C语言编写的用户定义函数

  Second, each query is going to require a full table scan, because MySQL can't use an index for your query.其次，每个查询需要进行全表扫描，因为MySQL不能使用索引查询。 So, unless your table is very small, this will not be fast.所以，除非你的表是非常小的，这不会是快。

   

  原文链接:http://www.16kan.com/question/detail/275365.html