To: pgsql-sql@postgresql.org
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From: Jasen Betts <jasen@xnet.co.nz>
Newsgroups: gmane.comp.db.postgresql.sql
Subject: Re: Extending Regular Expression bounds limit of 255.
Date: 30 May 2010 10:37:59 GMT
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On 2010-05-29, Tim Landscheidt <tim@tim-landscheidt.de> wrote:
> Jasen Betts <jasen@xnet.co.nz> wrote:
>
>>> It looks like most of our tools are using the Perl version of regular
>>> expressions with an upper limit of a bound being 32766.  Is there any way to
>>> change this in PG?  Or can I change from POSIX to Perl?
>
>> perhaps you can do something in pl-perl?
>
>> posix regular expressions are different to perl regular expressions in
>> several ways.
>
> Another last resort possibility would of course be to "pre-
> compile" the regular expressions from "A{2000}" to
> "A{255}A{255}A{255}A{255}A{255}A{255}A{255}A{215}" 

 (A{200}){10}
 
 might work better.

> (with the headaches of "A{1000,2000}" left as an exercise to the read-
> er :-)).

easy enoungh to write, but probably easy to write an expression with
factorial complexity too, but this one should work, having at worst
two ways of matching any string.

 (A{200}){5,9}A{0,200} 

but 

 (A{5,10}){200}
 
is asking for trouble.