Re: Review: UNNEST (and other functions) WITH ORDINALITY

On Mon, Aug 5, 2013 at 1:31 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

>
> This looks like really nice work.

It does. It's functionally equivalent to my attempt but with much better
comments and cleaner code.

But it doesn't seem to cover the case I was stumped on, namely "nulls
first" appearing in a place where two unreserved keywords can appear
consecutively. This doesn't happen for WITH_* before "with" is a reserved
keyword.

Looking into it a bit I see that the case I was most worried about is
actually a non-issue. We don't support column aliases without "AS" unless
the alias is completely unknown to the parser. That seems a bit of a
strange rule that must make the syntax with the missing AS pretty
unreliable if people are looking for code that will continue to work in
future versions. I never knew about this.

The only other case I could come up with in my regression tests is pretty
esoteric:

CREATE COLLATION nulls (locale='C');
ALTER OPERATOR CLASS text_ops USING btree RENAME TO first;
CREATE TABLE nulls_first(t text);
CREATE INDEX nulls_first_i ON nulls_first(t COLLATE nulls first);

I'm not 100% sure there aren't other cases where this can occur though.

--
greg