CODEWITHSUNDEEP
databasehashredisnosql
user1953051
user1953051

Reputation: 611

How to sort hash values in Redis?

Here I have 3 Hashes and I used sadd to define the relations

 hmset user:1 name Jack
 hmset category:1 name music
 hmset instrument:1 name guitar 

 sadd user:1:category 1 sadd category:1:instrument 1

So in this case if I want to get user's instrument how should write my command? this didnt work 

Sort User:1:Category:Instrument Get Category*:->Instrument

Upvotes: 1

Views: 1311

Answers (1)

Itamar Haber
Itamar Haber

Reputation: 49942

Firstly, it is unclear from your question what it is that you're trying to do - perhaps adding more details about the data's structure and the end result that you're looking for would help. Try explaining the relationships between the user, category and instruments entities and the type of query you're looking to run.

That said, there are several problems that are apparent as is:

  1. Note that key names are case sensitive so when calling SORT (or any command for that matter) make sure you use key names with the same case you used to create the keys. That means the foo, Foo, FOO and FoO are all different key names.

  2. Your SADD statement will result in a single Set with the following contents:

    127.0.0.1:6379> sadd user:1:category 1 sadd category:1:instrument 1
(integer) 3
127.0.0.1:6379> smembers user:1:category
1) "category:1:instrument"
2) "1"
3) "sadd"

To create multiple sets you'll need to issue separate SADD commands, once for each Set.

  1. Use Sets to express 1:N relationships, e.g. a user can have multiple instruments. To express a 1:1 relationship, simply add a field to your Hash, i.e.:

    127.0.0.1:6379> hmset user:1 name Jack instrument 1
OK
127.0.0.1:6379> hgetall user:1
1) "name"
2) "Jack"
3) "instrument"
4) "1"

On the other hand, if your user can have N instruments, use a Set:

    SADD user:1:instruments 1 2 3

  1. Assuming a user has multiple instruments, getting the instruments' names is done with SORT like so:

    SORT user:1:instruments BY nosort GET instrument:*->name

Upvotes: 2

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