> A quick look at the grammar suggests that the key problem is the
> opt_timezone production --- it might be that if we removed that in
> favor of spelling out the alternatives at the call sites, the conflict
> would go away. bison-fu is all about postponing shift/reduce decisions
> until you've seen enough to be sure ...
>
> regards, tom lane
Yes, if we can change opt_timezone and related production rules,
it is a better choice.