Re: psql can't subtract

On 03/25/2011 09:57 AM, Richard Huxton wrote:
> On 25/03/11 15:29, Rob Sargent wrote:
>> Running 9.0.3 (client and server)
>
>> select distinct
>> substring(
> ...
>> position( 'xmlns=' in substring(xml_text,1,300)) + length('xmlns="'),
>> 100))) -1
> ...
>> gives
>> ERROR: negative substring length not allowed.
>
> If there is no match the initial position will be zero. Minus one will
> give you a negative substring length.
>
Of course.  One lousy malformed input record.  The speed at which the
failure occurred lead me to think it was a parsing issue.  Turns out the
bogus record was "near the front of the queue".

Thanks