Re: Another regexp performance improvement: skip useless paren-captures - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Another regexp performance improvement: skip useless paren-captures
Date
Msg-id CA+TgmoYH9QJu8G14tW7oY+aomEu0nbet=iLwiAW8fFN5NAQT=w@mail.gmail.com
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In response to Re: Another regexp performance improvement: skip useless paren-captures  (Andrew Dunstan <andrew@dunslane.net>)
Responses Re: Another regexp performance improvement: skip useless paren-captures  (Tom Lane <tgl@sss.pgh.pa.us>)
Re: Another regexp performance improvement: skip useless paren-captures  (Andrew Dunstan <andrew@dunslane.net>)
List pgsql-hackers
On Thu, Aug 5, 2021 at 9:43 AM Andrew Dunstan <andrew@dunslane.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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