пн, 28 мар. 2022 г. в 15:01, hubert depesz lubaczewski <depesz@depesz.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.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.
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.
