Temporary User Accounts: MongoDB vs Redis

Question

I'm developing an application with NodeJS, ExpressJS and MongoDB. Currently I'm working on the user registration process. I would like to store the user account temporary until the user has verified his email address, if the email address is not verified within a certain amount of time, I would like to remove the temporary account.

Currently I've following two ideas to solve the issue:

• Creating a mongoose TempUserModel (besides the UserModel), i.e. if the user does the registration a temp user will be created, as soon as the user verified his email address, the temporary user account will be copied to the real Users collection. Some cronjobs could be setup to delete not verified user accounts after a certain amount of time (probably there are better solutions to let expire a mongodb record)

• Setup redis to store the temporary user account data, as soon as the email address get verified, a new user will be created in mongodb. With this solution an expire date could be set to remove not verified accounts after a certain amount of time)

Is it better to store a temporary user account in Redis or in MongoDB?

Answer 1

I would recommend storing the temporary user accounts in MongoDB. Storing them in MongoDB has three advantages over Redis:

1. If you store a temporary user in MongoDB, it will be very easy to convert them to a real user once they have verified. In fact, you could even have the temporary users and verified users share the same schema, with a has_verified field in that schema being the only difference between the two kinds of users. Changing has_verified to true is a lot easier than saving data from Redis to Mongo.
2. If you are not already planning to create a Redis database for your project, you will only have to maintain MongoDB. Maintaining MongoDB requires less effort and fewer computation resources than maintaining both Redis and MongoDB.
3. If you ever make changes to your user schema in the future, it would be easier to only make those changes in once place, i.e. MongoDB, rather than to make those changes in two places.