Re: PostgreSQL vs SQL Standard

On Sun, Jun 10, 2018 at 11:32:56AM -0400, Tom Lane wrote:
> Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> writes:
> > I beat at the grammar a bit to see what it would take to fix it at least
> > to the extent of allowing a_expr ColId in a select list after removing
> > postfix ops. It looked like it was doable by making these keywords more
> > reserved (all of which are already reserved words per spec):
> > DOUBLE, DAY, FILTER, HOUR, MINUTE, MONTH, OVER, PRECISION, SECOND,
> > VARYING, WITHIN, WITHOUT, YEAR
>
> Yeah, a side effect of allowing "a_expr ColId" is that we can expect,
> going forward, that a lot of new keywords are going to have to become
> fully reserved that otherwise wouldn't have to be. This is particularly
> a problem because of the SQL committee's COBOL-hangover tendency to
> invent new syntax that involves sequences of keywords; we usually
> don't have a good way to deal with that short of making the first
> keyword(s) reserved.
>
> It's arguable that going down that path will, in the long run, lead to
> breaking more applications (via their table/column names suddenly becoming
> reserved in some new version) than we rescue from having to quote their
> SELECT aliases. At the very least we need to recognize that this is far
> from cost-free.
>
> (wanders away wondering exactly what parsing technology the SQL committee
> thinks implementations use...)

If you're wondering why people think specifications that don't include
a reference implementation are a bad idea...

Best,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778

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