for postgres, i highly recommend the rum index over the core fts. rum is written by postgrespro, who also wrote core fts and json indexing in pg.

    https://github.com/postgrespro/rum

rum handles +20mil pdf pages, interactively.

Pleasantly surprised that RUM is just a drop-in replacement for the built-in GIN index, you can still use Postgres' native FTS operations with it.

Sounds very interesting. Never heard of rum, thank you for suggesting it.