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> Further, when we exhibited at RailsWorld 2023, there was a definite "blood in the water" vibe regarding Redis and the assumption that you'd automatically need a Redis server running alongside your Rails application.

I've only worked on one production Rails application in my career (and it did use Redis!), so I'm way out of the loop – is the ecosystem turning against Redis from a business perspective (I know there have been some license changes), or is it a YAGNI situation, or something else?

IIRC we used it mainly with Rescue to schedule asynchronous jobs like indexing, transcoding, etc., but it seemed like a neat tool at the time.

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It's a little YAGNI - I think the biggest driver of Redis in community was for exactly what you described aysnc jobs and the tool most folks reached for was Sidekiq.

The 2024 Rails community survey just came out and Redis is still listed as the top datastore that people use in their apps.

FWIW - we found that while many folks are _using_ Redis in their apps, they're just using it for things like Sidekiq and not actually taking advantage of it for holding things like real time leaderboards, vector db functions, etc. so it's a little fuzzy the actual usage.

I think it's purely a simplicity thing.

Right now, most rails setups with decent traffic will have frontend boxes, a sql db, a KV store (redis or memcached), and a cache store pointed at the kv store, with, annoyingly, very different usage patterns than typical KV store usage, eg for maintaining api quotas or rate limiting.

Disk performance has gotten fast enough and SQL performance has gotten good enough that there's a movement to drop the KV store and split the usages (for traditional KV use and also backing a cache) to the sql db and disk, respectively. Plus new nvme disks are almost as fast and still much cheaper than ram so you can cache more.

I’ve found it useful in the past as basically very-smart (i.e. stuff like expiration built-in) shared memory. Potentially with clustering (so, shared across multiple machines).

In the era of k8s, and redis-as-a-service, though? It’s gonna be “shared memory” on another VM on another rack. At that point, just read & write a damn file off S3, you’ve already abandoned all hope of efficient use of resources.

More people should be using RocksDB as SSD these days are fast and you can have much larger KV store running off of it.

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