Re: Improving isolationtester's data output

On Tue, Jun 15, 2021 at 09:43:31PM -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On 2021-06-15 19:26:25 -0400, Tom Lane wrote:
> >> Going forward it wouldn't be a problem, but back-patching isolation
> >> test cases might find it annoying. On the other hand, my nearby
> >> patch to improve isolation test stability is already going to create
> >> issues of that sort. (Unless, dare I say it, we back-patch that.)
>
> > It might be worth to back-patch - aren't there some back branch cases of
> > test instability? And perhaps more importantly, I'm sure we'll encounter
> > cases of writing new isolation tests in the course of fixing bugs that
> > we'd want to backpatch that are hard to make reliable without the new
> > features?
>
> Yeah, there absolutely is a case to back-patch things like this. Whether
> it's a strong enough case, I dunno. I'm probably too close to the patch
> to have an unbiased opinion about that.
>
> However, a quick look through the commit history finds several places
> where we complained about not being able to back-patch isolation tests to
> before 9.6 because we hadn't back-patched that version's isolationtester
> improvements. I found 6b802cfc7, 790026972, c88411995, 8b21b416e without
> looking too hard. So that history certainly suggests that not
> back-patching such test infrastructure is the Wrong Thing.

I'm +1 for back-patching this class of change. I've wasted time adapting a
back-patch's test case to account for non-back-patched test infrastructure
changes. Every back-patch of test infrastructure has been a strict win from
my perspective.