Re: Death by regexp_replace

9.2.6

On Fri, Jan 15, 2016 at 3:48 PM, Kevin Grittner <kgrittn(at)gmail(dot)com> wrote:

> On Fri, Jan 15, 2016 at 9:33 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> >> *WARNING DO NOT DO THIS ON A PRODUCTION BOX*
> >> select regexp_replace('VODI GR,VOD LN,VOD LN,VODN MM,VODPF US,VOD US,VZC
> >> LN', '([^,]+)(,*\1)+', '\1');
>
> > This responds to cancel just fine for me.
>
> > (FWIW, I think you probably wanted ,+ not ,* in the regex, else there's
> > practically no constraint there, leading to having to consider O(N^2)
> > or more possibilities.)
>
> On master (commit cf7dfbf2) it responds to pg_cancel_backend(),
> but it seems to be in an endless loop until you do that.
>
> --
> Kevin Grittner
> EDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>