Re: BUG #17450: SUBSTRING function extracting lesser characters than specified

пн, 28 мар. 2022 г. в 15:01, hubert depesz lubaczewski <depesz(at)depesz(dot)com>:

> On Mon, Mar 28, 2022 at 10:30:07AM +0000, PG Bug reporting form wrote:
> > The following bug has been logged on the website:
> >
> > Bug reference: 17450
> > Logged by: Suman Ganguly
> > Email address: ganguly(dot)04(at)gmail(dot)com
> > PostgreSQL version: 10.17
> > Operating system: x86_64-pc-linux-gnu
> > Description:
> >
> > select substring('123456', 0 , 5)
> > On running this, Postgres returns '1234'
> > Expecting '12345' to be returned as per the documentation
>
> Well, the problem is that you're trying to provide character number 0,
> which is leading to bad results.
>
> substring works on base-1 numbering.
>
Yes, the behavior expected in a report seems to be right. I've attached a
very small fix for that issue. Probably it should be backpatched into all
versions having 4bd3fad80e5c i.e. since v11.

--
Best regards,
Pavel Borisov

Postgres Professional: http://postgrespro.com <http://www.postgrespro.com>