documentation/About-the-database-and-tables.md

Invidious needs one PostgreSQL database with five tables.

channel_videos Stores truncated video info, used to create user feeds
channels Stores UCID and author name
nonces Keeps track of tokens issued to prevent CSRF
users Stores user info, such as preferences, username, subscriptions
videos Stores video cache, used to create "top" page

The table videos grows a lot and needs the most storage. You can clean it up using following commands:

$ sudo -i -u postgres
$ psql invidious -c "TRUNCATE TABLE videos"
$ exit