> If what you want is persistent k/v, then there are already tons databases that can do that.

Are there? What's a good, mainstream, persistent k/v for cheap single-node instances? PostgreSQL's KV support isn't good enough, Cassandra and MongoDB expect to be set up as a cluster and have all the overhead of that, BikeshedDB is alpha and I won't touch their upstream for obvious reasons, CouchDB is pretty much unmaintained, ....

How about LMDB ? It’s single writer/multiple reader, very fast and reliable.

This thread is my first time hearing of it, it doesn't seem particularly established/mature (e.g. I can't find cloud services offering managed instances, whereas there are plenty of those for Redis)

You didn't read enough what it actually is. Its embedded db like rocksdb.

Then it's hardly a substitute for Redis.

You put redis on top of it.

Are you suggesting that there's no need for Redis to integrate persistent-storage support because every user should download some library and patch the Redis source themselves? And that would somehow be better?

I'm suggesting you haven't read enough before replying, just like I did on my first comment. See "Myrocks" as an example of what the first user meant with lmdb. Replace "mysql -> redis" and "rocksdb -> lmdb".

I'm looking for a standard, well-known, drop-in product - that's what Redis is, that's why persistent storage support in Redis is interesting. If I have to search up some combination thing then it's already a non-starter.

This is pointless.

RocksDB?

RocksDB is cool but it seems to be more of a toolkit for building your own K/V store than a standalone product like Redis?

RocksDB, Badger if you want embedded; which seems to be a more popular mechanism among kv-stores.

LMDB.

FoundationDB, etcd, consul in single node mode.

I'm not looking for embedded, we're talking about a Redis substitute. etcd/consul feel oriented towards running as a cluster and I'd expect overhead for that. FoundationDB is potentially a good shout, but it's not that established, e.g. it doesn't seem to be available in a managed way in cloud hosting environments.

KV Stores seem to be in a kind of split place, existing either as embedded, or full cluster mode. There isn’t really a “sqlite” or “postgres” of persistent KV stores. Cloud providers ship their own proprietary KV-stores: Dynamo in AWS, Bigtable in GCP. If you are ok with hosted, Scylla is also an option.

I’m always shocked that people use Redis for anything other than an ephemeral cache.

Your second paragraph follows from your first - people use Redis in this space because it's the closest thing there is to an "sqlite" or "postgres" for KV. Which is why I think Redis with persistence actually makes a lot of sense and fills a gap in the market.