that's not how this works. files are stored in s3, metadata in postgres
J/K. It could be a really good back-end option for Supabase's S3 front end. A lot of PG clients don't support proper "streaming" and looking at the codebase it's TypeScript.. postgres.js is the only client nearing "performant" I'm aware of(last I looked) on Node.js but it's not clear it supports streaming outside "Copy" per the docs. Support could be added to the client if missing.
Edit: Actually it could be a good option for your normal uploads too. Docs talk about it being ideal for 6Mb or smaller files? Are you using bytea or otherwise needing to buffer the full upload/download in memory? Streaming with Lob would resolve that, and you can compute incremental hash sums for etags and etc. Lob has downsides and limitations but for a very large number of people it has many great benefits that can carry them very far and potentially all the way.
Then for GDPR, when you delete a user, the associated storage can be deleted.
One could cobble this together with triggers, some kind of external process, and probably repetititious code so there is one table of metadata per "owning" id, although it would be nice to be packaged.
The source of truth also matters here - if it's the database or the underlying s3 bucket. I think having the underlying storage bucket to be the source of truth would be more useful. In that scenario we would sync the metadata in the database to match what's actually being stored and if we notice metadata of a object missing, we add that in as opposed to deleting the object in storage. This would make it easier for you to bring in your own s3 bucket with existing data and attach it to Supabase storage.