Re: Standard REGEX functions

On 12/18/22 15:24, Tom Lane wrote:
> Vik Fearing <vik@postgresfriends.org> writes:
>> Are there any objections to me writing a patch to add SQL Standard
>> regular expression functions even though they call for XQuery and we
>> would use our own language?
> 
> Yes.  If we provide spec-defined syntax it should have spec-defined
> behavior.  I really don't see the value of providing different
> syntactic sugar for functionality we already have, unless the point
> of it is to be spec-compliant, and what you suggest is exactly not
> that.

I was expecting this answer and I can't say I disagree with it.

> I recall having looked at the points of inconsistency (see 9.7.3.8)

Oh sweet!  I was not aware of that section.

> and thought that we could probably create an option flag for our regex
> engine that would address them, or at least get pretty close.  It'd
> take some work though, especially for somebody who never looked at
> that code before.
Yeah.  If I had the chops to do this, I would have tackled row pattern 
recognition long ago.

I don't suppose project policy would allow us to use an external 
library.  I assume there is one out there that implements XQuery regular 
expressions.
-- 
Vik Fearing