many-to-many - 如何在redis中建立多对多关系

Question

在关系数据库中，我有一个用户表、一个类别表和一个执行多对多关系的用户类别表。

这个结构在Redis中是什么形式的？

Answer 1

对于 Redis，关系通常由集合表示。一套可以用表示单向关系，因此每个对象需要一组表示多对多关系。

尝试将关系数据库模型与 Redis 进行比较是毫无用处的数据结构。使用 Redis，一切都以非规范化的方式存储。示例:

# Here are my categories
> hset category:1 name cinema  ... more fields ...
> hset category:2 name music   ... more fields ...
> hset category:3 name sports  ... more fields ...
> hset category:4 name nature  ... more fields ...

# Here are my users
> hset user:1 name Jack   ... more fields ...
> hset user:2 name John   ... more fields ...
> hset user:3 name Julia  ... more fields ...

# Let's establish the many-to-many relationship
# Jack likes cinema and sports
# John likes music and nature
# Julia likes cinema, music and nature

# For each category, we keep a set of reference on the users
> sadd category:1:users 1 3
> sadd category:2:users 2 3
> sadd category:3:users 1
> sadd category:4:users 2 3

# For each user, we keep a set of reference on the categories
> sadd user:1:categories 1 3
> sadd user:2:categories 2 4
> sadd user:3:categories 1 2 4

一旦我们有了这个数据结构，就可以很容易地使用集合代数查询它:

# Categories of Julia
> smembers user:3:categories
1) "1"
2) "2"
3) "4"

# Users interested by music
> smembers category:2:users
1) "2"
2) "3"

# Users interested by both music and cinema
> sinter category:1:users category:2:users
1) "3"