How to Reverse Lookup in Redis?

Question

Is it possible to use Redis to lookup by key OR value? I need to store a master list of email addresses, assign a UUID to each address, but be able to find the ID OR ADDRESS by using the other piece of data. I cannot find a definitive "yes" or "no." Any examples would be appreciated.

Answer 1

You'll want to create 2 hashmaps:

1. Hashmap from UUID to email (uuid_to_email)
2. Hashmap from email to UUID (email_to_uuid)

For example:

> hset uuid_to_email 39315120-9581-11e3-9c4e-0002a5d5c51b [email protected]
> hset email_to_uuid [email protected] 39315120-9581-11e3-9c4e-0002a5d5c51b

Then to retrieve the value, use the hashmap that maps from the value you have. If you have a UUID, use uuid_to_email:

> hget uuid_to_email 39315120-9581-11e3-9c4e-0002a5d5c51b
"[email protected]"

If you have an email, use email_to_uuid:

> hget email_to_uuid [email protected]
"39315120-9581-11e3-9c4e-0002a5d5c51b"