On Thu, Mar 3, 2011 at 2:16 AM, Heikki Linnakangas <heikki.linnakangas@xxxxxxxxxxxxxxxx> wrote: > On 03.03.2011 09:12, daveg wrote: >> >> Question: what would be the consequence of simply patching out the setting >> of this flag? Assuming that the incorrect PD_ALL_VISIBLE flag is the only >> problem (big assumption perhaps) then simply never setting it would at >> least >> avoid the possibility of returning wrong answers, presumably at some >> performance cost. We possibly could live with that until we get a handle >> on the real cause and fix. > > Yes. With that assumption. > > If you really want to do that, I would suggest the attached patch instead. > This just disables the optimization in seqscans to trust it, so an > incorrectly set flag won't affect correctness of query results, but the > flag is still set as usual and you still get the warnings so that we can > continue to debug the issue. This. The mis-set flag can is likely a bug/concurrency issue etc, but could also be a symptom of more sinister data corruption. I did various vacuum experiments all day yesterday on my windows workstation and was not able to produce any mis-flags. I trust iscsi more than nfs, but maybe there is a connection here that is hardware based. hm. do you think it would be helpful to know what is causing the all_visible flag to get flipped? If so, the attached patch shows which case is throwing it... merlin
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