On Wed, Feb 08, 2017 at 11:22:56AM -0500, Tom Lane wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
> > On Wed, Feb 8, 2017 at 4:24 AM, Pantelis Theodosiou <ypercube@gmail.com> wrote:
> >> I'm not advocating it but I don't see how introducing new SQL keywords
> >> breaks backwards compatibility.
>
> > It does at least a little bit.
>
> Yes. I think a new set-operation keyword would inevitably have to
> be fully reserved --- UNION, INTERSECT, and EXCEPT all are --- which
> means that you'd break every application that has used that word as
> a table, column, or function name.
I've long wanted a SYMMETRIC DIFFERENCE join type, that being the only
elementary set operation not included in join types, but nobody at the
SQL standards committee seems to have cared enough to help.
> Generally speaking, we try very darn hard not to introduce new
> reserved words that are not called out as reserved in the SQL
> standard. (And even for those, we've sometimes made the grammar
> jump through hoops so as not to reserve a word that we didn't
> reserve previously.)
We just never know what new keywords the standards committee will
dream up, or what silliness they'll introduce in the grammar :/
Best,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com
Remember to vote!
Consider donating to Postgres: http://www.postgresql.org/about/donate