Re: conflict with recovery when delay is gone

On Fri, 2020-11-13 at 15:24 +0200, Radoslav Nedyalkov wrote:
> On a very busy master-standby setup which runs typical olap processing -
> long living , massive writes statements,  we're getting on the standby:
> 
>  ERROR:  canceling statement due to conflict with recovery
>  FATAL:  terminating connection due to conflict with recovery
> 
> The weird thing is that cancellations happen usually after standby has experienced 
> some huge delay(2h), still not at the allowed maximum(3h). Even recently run statements
> got cancelled when the delay is already at zero.
> 
> Sometimes the situation got relaxed after an hour or so.
> Restarting the server instantly helps.
> 
> It is pg11.8, centos7, hugepages, shared_buffers 196G from 748G.
> 
> What phenomenon could we be facing?

Hard to say.  Perhaps an unusual kind of replication conflict?

What is in "pg_stat_database_conflicts" on the standby server?

Yours,
Laurenz Albe
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