This needs 2021 in the title, but it's actually really out of date and might as well have 2011 in the title. Redis has modules which can provide a bunch of extr

This needs 2021 in the title, but it's actually really out of date and might as well have 2011 in the title. Redis has modules which can provide a bunch of extra capabilities that do allow querying, indexing, etc. [Full disclosure: I used to work on Redis and created much of the basis of those modules, but haven't been involved in the past 5 years]