Re: select_common_type()'s behavior doesn't match the documentation

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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