That paper's definition of rewriting isn't the same as postgres' (they even say that: "The work presented here should not be confused with the query rewrite fac

That paper's definition of rewriting isn't the same as postgres' (they even say that: "The work presented here should not be confused with the query rewrite facility of POSTGRES [SJGP90]."). Flattening subqueries and views happens during planning in postgres. Source: I'm a PostgreSQL Developer.