📚 Database Sharding to improve scalability and performance

[sorbaugh]

As bigger and bigger Nextcloud installations are being set up, we need to make efforts and think about how to make Nextcloud more scalable and performant. We should look into database sharding to allow the database to handle larger amounts of data, higher number of transactions, etc.

As a first step it would be good to identify what tables would be best suited for sharding.

EDIT: Linking @icewind1991 's gist with filecache's query analysis: https://gist.github.com/icewind1991/f9583eab9cf80455743812b22664ea0e

Subtasks

• [x] #43562
• [x] #43563
• [x] #43692
• [x] #43693
• [ ] #43694
• [ ] Make it a config switch to block direct oc_fiecache access
• [ ] Add a flag to the app config to tell whether they are sharding compatible