If you read through it, this is a change to the Citus cstore_fdw extension, which stores data outside PostgreSQL and queries it using the PostgreSQL Foreign Data Wrapper API (see https://wiki.postgresql.org/wiki/Foreign_data_wrappers).

So it's impressive, but it isn't a performance improvement for core PostgreSQL, or data stored natively in PostgreSQL (in particular, cstore_fdw is not very flexible - from the README for that project: "Note. We currently don't support updating table using INSERT, DELETE, and UPDATE commands.")