PostgreSQL, unfortunately, can't do that. But if it were to happen, it'd not be in the rewriter. It'd not make sense to attempt such transformations before som

PostgreSQL, unfortunately, can't do that. But if it were to happen, it'd not be in the rewriter. It'd not make sense to attempt such transformations before some other optimizations (like flattening of subqueries et al), and that happens in the optimization step