Date: Mon, 28 Mar 2022 13:01:20 +0200
From: hubert depesz lubaczewski <depesz@depesz.com>
Sender: depesz@depesz.com
To: ganguly.04@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17450: SUBSTRING function extracting lesser characters than
 specified
Message-ID: <20220328110119.GA28018@depesz.com>
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References: <17450-69df48455c28fbea@postgresql.org>
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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.04@gmail.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.

depesz