While working on TRUNCATE with ONLY, I said to myself, hmm, when writing
TRUNCATE ONLY a, b
it might be a bit confusing whether the ONLY refers to a or both a and
b. Then I noticed that the SQL standard requires parentheses, like
TRUNCATE ONLY (a), b
which is clearer. While we support that in gram.y, I don't see it
anywhere in the documentation.
Should we document this and emphasize it as having more clarity?
