On Thu, Mar 12, 2015 at 5:56 PM, Andres Freund <and...@2ndquadrant.com> wrote: >> > Any chance that the new nodes also use a different kernel version or >> > such? >> >> They may differ, but that doesn't seem likely to be relevant, at least >> to me. > > There've been some issues with seek(END) sometimes returning the wrong > length in the past. And I've seen a report that might indicate a similar > bug has been reintroduced. That could certainly cause such anerror.
It seems that I failed to take account of the fact that these cases all involved Ubuntu 14.04 LTS (that wasn't clear to me before, but I've verified that that's the case now), which is a small minority of the kernels our instances use. I've verified that the issue arises independently of point release, including on earlier point releases from about a year ago, so I was hasty in suggesting that there was a regression in the latest point releases. I'm still going to get a back trace here, because it seems reasonable to suppose that there is a Postgres bug even still - it may be that whatever differences are in the 14.04 kernel are enough to make a previously latent bug trip this code up. Plenty of people are using Ubuntu 14.04 LTS with Postgres without seeing this issue, or any other issue, and there is no other issue with the kernel that I know of. The issue continues to occur as new instances with this configuration are deployed. I should also add that my temporary remediation ("VACUUM FULL pg_auth_members;") works consistently, as new cases start to crop up. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers