CODEWITHSUNDEEP
redis
Asym
Asym

Reputation: 1938

Redis - Sort and filter hash store using string attribute

I have a redis hash store that looks like Item:<id>, with attribute name. I want to filter the hash store by a prefix for name attribute. What I'm trying to do is store the name (lowercased) in a separate Z-set called Item:::name while setting the score to 0. By doing this, I'm successfully able to get the desired result using ZRANGEBYLEX however I'm unable to map the results back to the original Items. How should I go about implementing something like this?

I've seen multiple autocomplete examples for Redis which require the same functionality but without linking the words back to an actual Item (hash in this case)

Upvotes: 0

Views: 445

Answers (1)

Ersoy
Ersoy

Reputation: 9594

In sorted sets the member can't be duplicated, it has to be unique. So different users with the same name will cause problem.

My suggestion requires application layer coding to parse response array and executing hash commands (it will be like secondary indexes);

127.0.0.1:6379> HSET user:1 name jack
(integer) 1
127.0.0.1:6379> HSET user:2 name john
(integer) 1
127.0.0.1:6379> HSET user:3 name keanu
(integer) 1
127.0.0.1:6379> HSET user:4 name jack
(integer) 1
127.0.0.1:6379> ZADD item:names 0 jack::user:1 0 john::user:2 0 keanu::user:3 0 jack::user:4
(integer) 4
127.0.0.1:6379> ZRANGE item:names 0 -1 WITHSCORES
1) "jack::user:1"
2) "0"
3) "jack::user:4"
4) "0"
5) "john::user:2"
6) "0"
7) "keanu::user:3"
8) "0"
127.0.0.1:6379> ZRANGEBYLEX item:names [jack [jo
1) "jack::user:1"
2) "jack::user:4"

At the end you will have name::hash-key formatted array elements. At application layer if you separate each element to two substrings by using ::(any other string such as !!! or || etc) you will have user:1 and user:4.

127.0.0.1:6379> HGETALL user:1
1) "name"
2) "jack"
127.0.0.1:6379> HGETALL user:4
1) "name"
2) "jack"
127.0.0.1:6379>

Upvotes: 2

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