Date: Sun, 3 Apr 2022 09:32:56 -0700
From: Andres Freund <andres@anarazel.de>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>,
	John Naylor <john.naylor@enterprisedb.com>,
	Peter Geoghegan <pg@bowt.ie>,
	pgsql-hackers <pgsql-hackers@postgresql.org>,
	Robert Haas <rhaas@postgresql.org>
Subject: Re: A qsort template
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Hi,

On 2022-04-03 17:46:28 +1200, Thomas Munro wrote:
> On Sun, Apr 3, 2022 at 11:11 AM Andres Freund <andres@anarazel.de> wrote:
> > On 2022-04-03 09:45:13 +1200, Thomas Munro wrote:
> > > I think we just need to decide up front if we're in a situation that
> > > can't provide datum1/isnull1 (in this case because it's an expression
> > > index), and skip the optimised paths.  Here's an experimental patch...
> > > still looking into whether there are more cases like this...
> 
> I didn't find anything else.
> 
> Maybe it'd be better if we explicitly declared whether datum1 is used
> in each tuplesort mode's 'begin' function, right next to the code that
> installs the set of routines that are in control of that?  Trying that
> in this version.  Is it clearer what's going on like this?

Seems an improvement.


> > I'm a bit worried that none of the !ubsan tests failed on this...
> 
> In accordance with whoever-it-was-that-said-that's law about things
> that aren't tested, this are turned out to be broken already[1].

Yea :/.


Would be good to get this committed soon, so we can see further ubsan
violations introduced in the next few days (and so I can unblock my local dev
tests :P).

Greetings,

Andres Freund