That's absolutely right! mvsqlite is a cool project but it doesn't make good use of FoundationDB in a way, which I find a bit unfortunate what a nice piece of software it is!

> This is presumably why database metadata (DDL) isn't currently persisted, because those structures aren't normal tables.

Yes, although perhaps a fun fact that all database metadata in Postgres is actually stored as standard tables, the so called system catalog: https://www.postgresql.org/docs/current/catalogs.html.

I'm still mulling over how to implement DDL persistence but one possible way would be to change the actual system catalog tables to be backed by FDB instead, and rely on some cache on the nodes to avoid round tripping to FDB to get metadata for each query.

As you can imagine though the system catalog is quite deeply intertwined with Postgres as a whole so remains to be seen if this is even doable. The alternative would be a more complicated design where the data is stored in some custom format in FDB and then synced by each node into the system catalog.

So this is wrong. The heap storage is replaced.