Re: [HACKERS] More replication race conditions

On Sun, Aug 27, 2017 at 3:34 PM, Michael Paquier
<michael.paquier@gmail.com> wrote:
> On Sun, Aug 27, 2017 at 12:03 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> contains exactly no means of ensuring that the master's transaction has
>> been replayed on the standby before we check for its results.  It's not
>> real clear why it seems to work 99.99% of the time, because, well, there
>> isn't any frickin' interlock there ...
>
> I have noticed this one this morning, and I am planning to address it
> with a proper patch soonishly. (I am still fighting a bit to get
> dangomushi in a more stable stable, and things run slow on it, so it
> is good at catching race conditions of this kind).

Today's run has finished with the same failure:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=dangomushi&dt=2017-08-27%2018%3A00%3A13
Attached is a patch to make this code path wait that the transaction
has been replayed. We could use as well synchronous_commit = apply,
but I prefer the solution of this patch with a wait query.
-- 
Michael

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