MongoDB with redis

Question

Can anyone give example use cases of when you would benefit from using Redis and MongoDB in conjunction with each other?

Answer 1

Obviously there are far more differences than this, but for an extremely high overview:

For use-cases:

• Redis is often used as a caching layer or shared whiteboard for distributed computation.
• MongoDB is often used as a swap-out replacement for traditional SQL databases.

Technically:

• Redis is an in-memory db with disk persistence (the whole db needs to fit in RAM).
• MongoDB is a disk-backed db which only needs enough RAM for the indexes.

There is some overlap, but it is extremely common to use both. Here's why:

• MongoDB can store more data cheaper.
• Redis is faster for the entire dataset.
• MongoDB's culture is "store it all, figure out access patterns later"
• Redis's culture is "carefully consider how you'll access data, then store"
• Both have open source tools that depend on them, many of which are used together.

Redis can be used as a replacement for a traditional datastore, but it's most often used with another normal "long" data store, like Mongo, Postgresql, MySQL, etc.