VietMX Staff asked 3 years ago
Hashes are sort of like a key value store within a key value store. They map between string fields and string values. Field->value maps using a hash are slightly more space efficient than key->value maps using regular strings.
Hashes are useful as a namespace, or when you want to logically group many keys. With a hash you can grab all the members efficiently, expire all the members together, delete all the members together, etc. Great for any use case where you have several key/value pairs that need to grouped.
One example use of a hash is for storing user profiles between applications. A redis hash stored with the user ID as the key will allow you to store as many bits of data about a user as needed while keeping them stored under a single key. The advantage of using a hash instead of serializing the profile into a string is that you can have different applications read/write different fields within the user profile without having to worry about one app overriding changes made by others (which can happen if you serialize stale data).
