Re: Another regexp performance improvement: skip useless paren-captures

On 8/5/21 10:39 AM, Robert Haas wrote:
> On Thu, Aug 5, 2021 at 9:43 AM Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:
>> On 8/4/21 6:15 PM, Tom Lane wrote:
>>> Here's a little finger exercise that improves a case that's bothered me
>>> for awhile. In a POSIX regexp, parentheses cause capturing by default;
>>> you have to write the very non-obvious "(?:...)" if you don't want the
>>> matching substring to be reported by the regexp engine.
>> It's not obscure to perl programmers :-)
> Well, I consider myself a pretty fair perl programmer,

I also consider you one :-)

Perhaps I should have said "many perl programmers".

> and I know
> there's a way to do that, but I never do it, and I would have had to
> look up the exact syntax. So +1 from me for anything automatic that
> avoids paying the overhead in some cases.

Yeah, I'm not arguing against the idea. I also have to look it up,
mainly because there is such a huge amount of stuff that can follow
"(?", do "perldoc perlre" happens a lot when I'm doing that sort of work.

cheers

andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com