Re: Precedence of standard comparison operators

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Simon Riggs <simon(at)2ndQuadrant(dot)com>
Cc: Peter Eisentraut <peter_e(at)gmx(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Precedence of standard comparison operators
Date: 2015-02-26 17:23:37
Message-ID: 54EF5699.2060807@dunslane.net
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On 02/26/2015 10:56 AM, Tom Lane wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>> On 20 February 2015 at 20:44, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> Well, assuming that we're satisfied with just having a way to warn
>>> when the behavior changed (and not, in particular, a switch that can
>>> select old or new behavior)
>> I'm in favour of your proposed improvements, but I'm having a problem
>> thinking about random application breakage that would result.
>> Having a warn_if_screwed parameter that we disable by default won't
>> help much because if you are affected you can't change that situation.
>> There are too many applications to test all of them and not all
>> applications can be edited, even if they were tested.
> I find this argument to be unhelpful, because it could be made in exactly
> the same words against any non-backwards-compatible change whatsoever.
> Nonetheless, we do make non-backwards-compatible changes all the time.

That's true, we do. But finding out where apps are going to break is not
going to be easy. Reviewing a million lines of code to examine where
changes in operator precendence might affect you could be an enormous
undertaking for many users. I understand the need, but the whole
prospect makes me very, very nervous, TBH.

cheers

andrew

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