| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Andrew Dunstan <andrew(at)dunslane(dot)net> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Joel Jacobson <joel(at)compiler(dot)org> |
| Subject: | Re: Another regexp performance improvement: skip useless paren-captures |
| Date: | 2021-08-05 14:39:21 |
| Message-ID: | CA+TgmoYH9QJu8G14tW7oY+aomEu0nbet=iLwiAW8fFN5NAQT=w@mail.gmail.com |
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| Lists: | pgsql-hackers |
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, 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.
--
Robert Haas
EDB: http://www.enterprisedb.com
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