Tom Lane <tgl@sss.pgh.pa.us> wrote:
> This came up because some of my Salesforce colleagues were griping about
> the fact that UNION isn't commutative. They argue that the type
> resolution behavior ought not be sensitive at all to the ordering of the
> inputs. I'm not sure we can achieve that in general, but the current
> approach certainly seems more order-sensitive than it oughta be.
>
> Some trolling in the git history says that the last actual change in
> this area was in my commit b26dfb95222fddd25322bdddf3a5a58d3392d8b1 of
> 2002-09-18, though it appears the documentation has been rewritten more
> recently. It's a bit scary to be proposing to change behavior that's
> been stable for eleven years, but ...
>
> Thoughts?
The current behavior is bad enough to merit changing it. Not for
back-patch, of course.
--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company