Re: Why this regexp matches?!

On Mon, Feb 06, 2012 at 11:29:23AM +0000, Jasen Betts wrote:
> On 2012-02-04, hubert depesz lubaczewski <depesz@depesz.com> wrote:
> > select 'depesz depeszx depesz' ~ E'^(.*)( \\1)+$';
> >
> > what's worse:
> > $ select regexp_replace( 'depesz depeszx depesz', E'^(.*)( \\1)+$', E'\\1' );
> >  regexp_replace
> > ────────────────
> >  depesz
> > (1 row)
> >
> > I know that Pg regexps are limited, but even grep's regexps match this
> > correctly:
>
> whose grep?
>
> Postgres is BSD licence and that means they can't use the latest and
> greatest GPL libraries.

yes, I did use gnu grep. but it's hardly "latest and greatest" - there
is nothing very special about this regexp, aside from the fact, that
according to pg docs (how I read them) - it shouldn't match, but it
does.

depesz

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