In DB2, it seems possible to define a "clustering index" that determines how rows are physically ordered in the "table space" (the heap).
The documentation says: "When a table has a clustering index, an INSERT statement causes DB2 to insert the records as nearly as possible in the order of their index values."
It looks like a kind of "continuous CLUSTER/pg_repack". Is there something similar available or planned for PostgreSQL?
I forgot the links to DB2 documentation about clustering index: