Ok. Thanks for your help.
On Oct 11, 2012, at 3:31 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Evan D. Hoffman" <evandhoffman@gmail.com> writes:
>> Because we have both 9.0 and 9.1 running, and a query that succeeds
>> under 9.1 was failing under 9.0. Can I assume the answer then is
>> "no"?
>
> There are any number of reasons a query might work in version N and not
> in N-1. If you've got requirements like that, you should be developing
> on the oldest version you're worried about supporting ...
>
> regards, tom lane