Bloated pg_catalog.pg_largeobjects

Hello All,

I've got a cluster that's having issues with pg_catalog.pg_largeobject getting massively bloated. Vacuum is running OK and there's 700GB of free space in the table and only 100GB of data, but subsequent inserts seem to be not using space from the FSM and instead always allocating new pages. The table just keeps growing.

Is this a known thing, maybe something special about LOs?

Also, is the only way to recover space here a vacuum full on the table since it's a catalog table?

Thanks,