Thread: Add tests for UNBOUNDED syntax ambiguity

As many will be aware, there is a syntactic ambiguity in the SQL 
standard regarding the keyword UNBOUNDED.  Since UNBOUNDED is a 
non-reserved word, it could be the name of a function parameter and be 
used as an expression.  There is a grammar hack to resolve such cases as 
the keyword.

I brought this issue to the SQL standard working group, and a fix has 
been agreed.  (Since long-standing syntax obviously can't be changed, 
the fix is basically just an additional rule saying, "if you see this, 
it means the keyword".)  While working on that, I wrote a few test cases 
to explore this and check how PostgreSQL actually handles this.  I 
figure these test cases are worth committing so that we have a record of 
this and future grammar refactorings can maintain the behavior.

On 24/06/2021 12:01, Peter Eisentraut wrote:
> As many will be aware, there is a syntactic ambiguity in the SQL
> standard regarding the keyword UNBOUNDED.  Since UNBOUNDED is a
> non-reserved word, it could be the name of a function parameter and be
> used as an expression.  There is a grammar hack to resolve such cases as
> the keyword.
> 
> I brought this issue to the SQL standard working group, and a fix has
> been agreed.  (Since long-standing syntax obviously can't be changed,
> the fix is basically just an additional rule saying, "if you see this,
> it means the keyword".)

Nice!

> While working on that, I wrote a few test cases to explore this and
> check how PostgreSQL actually handles this.  I figure these test
> cases are worth committing so that we have a record of this and
> future grammar refactorings can maintain the behavior.

+1

- Heikki