Re: factorial function/phase out postfix operators?

On Wed, May 20, 2020 at 2:24 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Right; I'd done the same arithmetic. Since we currently have a total
> of 450 keywords of all flavors, that means we can make either 64%
> of them or 74.6% of them be safe to use as bare column labels. While
> that's surely better than today, it doesn't seem like it's going to
> make for any sort of sea change in the extent of the problem. So I was
> feeling a bit discouraged by these results.

I don't think you should feel discouraged by these results. They
assume that people are just as likely to have a problem with a
reserved keyword as an unreserved keyword, and I don't think that's
actually true. The 25.4% of keywords that aren't handled this way
include, to take a particularly egregious example, "AS" itself. And I
don't think many people are going to be sad if "select 1 as;" fails to
treat "as" as a column label.

Also, even if we only made 74.6% of these safe to use as bare column
labels, or even 64%, I think that's actually pretty significant. If I
could reduce my mortgage payment by 64%, I would be pretty happy. For
many people, that would be a sufficiently large economic impact that
it actually would be a sea change in terms of their quality of life. I
don't see a reason to suppose that's not also true here.[1]

I do like the idea of considering "can be a bare column label" as an
independent dimension from the existing keyword classification.
Presumably we would then have, in addition to the four existing
keyword productions, but then also a separate
bare_column_label_keyword: production that would include many of the
same keywords. One nice thing about that approach is that we would
then have a clear list of exactly which keywords can't be given that
treatment, and if somebody wanted to go investigate possible
improvements for any of those, they could do so. I think we'd want a
cross-check: check_keywords.pl should contain the list of keywords
that are expected to be excluded from this new production, so that any
time someone adds a new keyword, they've either got to add it to the
new production or add it to the exception list.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

[1] On the other hand, if I had 64% fewer ants in my picnic basket, I
would probably still be unhappy with the number of ants in my picnic
basket, so it all depends on context and perspective.