Re: Inval reliability, especially for inplace updates

On Tue, Jun 18, 2024 at 08:23:49AM -0700, Noah Misch wrote:
> On Mon, Jun 17, 2024 at 06:57:30PM -0700, Andres Freund wrote:
> > On 2024-06-17 16:58:54 -0700, Noah Misch wrote:
> > > That inplace150 patch turned out to be unnecessary. Contrary to the
> > > "noncritical resource releasing" comment some lines above
> > > AtEOXact_Inval(true), the actual behavior is already to promote ERROR to
> > > PANIC. An ERROR just before or after sending invals becomes PANIC, "cannot
> > > abort transaction %u, it was already committed".
> >
> > Relying on that, instead of explicit critical sections, seems fragile to me.
> > IIRC some of the behaviour around errors around transaction commit/abort has
> > changed a bunch of times. Tying correctness into something that could be
> > changed for unrelated reasons doesn't seem great.
>
> Fair enough. It could still be a good idea for master, but given I missed a
> bug in inplace150-inval-durability-atcommit-v1.patch far worse than the ones
> $SUBJECT fixes, let's not risk it in back branches.

What are your thoughts on whether a change to explicit critical sections
should be master-only vs. back-patched? I have a feeling your comment pointed
to something I'm still missing, but I don't know where to look next.