How do you search for keys with a value? For example get all KEYS where the value is “somevalue”

Question

   redis> SMEMBERS CO:1:A
    1) "1"
    2) "2"

   redis> SMEMBERS CO:2:A
    1) "1"
    2) "5"
    3) "6"

   redis> SMEMBERS CO:3:A
    1) "5"

   redis> SMEMBERS CO:4:A
    1) "1"

Now I want to find the keys where the value 1 exist

If I search with the values 1 then the result keys will be CO:1:A, CO:2:A and CO:4:A

How to get This?

Answer 1

Redis is not a relational database. You need to anticipate this access path, and maintain a reverse index.

# This is your index
SADD CO:1:A 1 2
SADD CO:2:A 1 5 6
SADD CO:3:A 5
SADD CO:4:A 1

# Here is the reverse index
SADD REV:1 1 2 4
SADD REV:2 1
SADD REV:5 2 3
SADD REV:6 2

Now you can query in reverse way:

SMEMBERS REV:1
1) "1"
2) "2"
3) "4"
... meaning CO:1:A. CO:2:A, CO:4:A