On Wed, Feb 08, 2017 at 11:22:56AM -0500, Tom Lane wrote: > Robert Haas <robertmh...@gmail.com> writes: > > On Wed, Feb 8, 2017 at 4:24 AM, Pantelis Theodosiou <yperc...@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 -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers