Re: [HACKERS] 9.4.1 -> 9.4.2 problem: could not access status of transaction 1

On Fri, Jun 5, 2015 at 2:47 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2015-06-05 14:33:12 -0400, Tom Lane wrote:
>> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> > 1. The problem that we might truncate an SLRU members page away when
>> > it's in the buffers, but not drop it from the buffers, leading to a
>> > failure when we try to write it later.
>
> I've got a fix for this, and about three other issues I found during
> development of the new truncation codepath.
>
> I'll commit the fix tomorrow.

OK. Then I think we should release next week, so we get the fixes we
have out before PGCon. The current situation is not good.

>> > I think we might want to try to fix one or both of those before
>> > cutting a new release. I'm less sold on the idea of installing
>> > WAL-logging in this minor release. That probably needs to be done,
>> > but right now we've got stuff that worked in early 9.3.X release and
>> > is now broken, and I'm in favor of fixing that first.
>
> I've implemented this, and so far it removes more code than it
> adds. It's imo also a pretty clear win in how understandable the code
> is. The remaining work, besides testing, is primarily going over lots
> of comment and updating them. Some of them are outdated by the patch,
> and some already were.
>
> Will post tonight, together with the other fixes, after I get back from
> climbing.
>
> My gut feeling right now is that it's a significant improvement, and
> that it'll be reasonable to include it. But I'd definitely like some
> independent testing for it, and I'm not sure if that's doable in time
> for the wrap.

I think we would be foolish to rush that part into the tree. We
probably got here in the first place by rushing the last round of
fixes too much; let's try not to double down on that mistake.

--
Robert Haas
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