Re: RLS Design

20MB messages to the list aren't that friendly.  Please don't do that
again, unless asked to.

FWIW, the above syntax is a nonstarter, at least unless we're willing to
make POLICY a reserved word (hint: we're not).  The reason is that the
ADD/DROP COLUMN forms consider COLUMN to be optional, meaning that the
column name could directly follow ADD; and the column type name, which
could also be just a plain identifier, would directly follow that.  So
there's no way to resolve the ambiguity with one token of lookahead.
This actually isn't just bison being stupid: in fact, you simply
cannot tell whether

     ALTER TABLE tab ADD POLICY varchar(42);

is an attempt to add a column named "policy" of type varchar(42), or an
attempt to add a policy named "varchar" with quals "42".