It basically boils down to deleting a bunch of files on disk. The fact that it is distributed doesn't affect efficiency too much; it is basically a delete sent to all nodes, followed by a two-phase commit.
The upside of deleting entire tables (chunks) like this is that you don't pay the same PostgreSQL vacuuming cost normally associated with row-by-row deletes.
The upside of deleting entire tables (chunks) like this is that you don't pay the same PostgreSQL vacuuming cost normally associated with row-by-row deletes.