Thread

Re: Changing the state of data checksums in a running cluster

Daniel Gustafsson <daniel@yesql.se> — 2026-05-29T20:08:11Z

> On 28 May 2026, at 13:51, Tomas Vondra <tomas@vondra.me> wrote:
> 
> On 5/28/26 13:28, Daniel Gustafsson wrote:
>>> On 26 May 2026, at 20:12, Tomas Vondra <tomas@vondra.me> wrote:
>> 
>>> I suppose this means we should not be updating the checksum state
>>> without emitting the barrier? I think all other places do that.
>> 
>> Good catch, it's indeed a bug, any state change must emit a procsignalbarrier
>> to maintain cluster consistency.  I ended up writing a test for this very case
>> as well.
> 
> Good.

I've pushed this now, along with your other findings, ahead of the beta1
deadline, buildfarm seems happy so far.

>>> I still don't understand why this needs DELAY_CHKPT_START ...
>> 
>> Having stared at this for some time, and going over old threads, I think this
>> is a mistake.  AFAICT though it cannot cause any error, so I'd lean towards
>> erring on the safe side by leaving as is and looking at removing in 20.  What
>> do you think?
>> 
> 
> I'd probably try to fix this for 19, otherwise it may be confusing
> people looking at the code in the future. We're still months from 19
> getting released. Ofc, maybe I'm underestimating the risk.

You're probably right.  Once beta1 is out I'll work on getting this fixed.

--
Daniel Gustafsson