[jamesblonde]

Some of these questions are informed by the Redis/DynamoDB or Postgres/MySQL world the author seems to inhabit.

Why would you want to do this? "I don’t know of any database built to handle hundreds of thousands of read replicas constantly pulling data."

If you want an open-source database with Redis latencies to handle millions of concurrent reads, you can use RonDB (disclaimer, I work on it).

"Since I’m only interested in a subset of the data, setting up a full read replica feels like overkill. It would be great to have a read replica with just partial data. It would be great to have a read replica with just partial data."

This is very unclear. Redis returns complete rows because it does not support pushdown projections or ordered indexes. RonDB supports these and distion aware partition-pruned index scans (start the transaction on the node/partition that contains the rows that are found with the index).

Reference:

https://www.rondb.com/post/the-process-to-reach-100m-key-loo...